СУПЕРОКСИДДИСМУТАЗА В КЛЕТКАХ РАСТЕНИЙ
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2006 ÖÈÒÎËÎÃÈß Ò î ì 48, ¹ 6 ÑÓÏÅÐÎÊÑÈÄÄÈÑÌÓÒÀÇÀ  ÊËÅÒÊÀÕ ÐÀÑÒÅÍÈÉ © Â. Â. Áàðàíåíêî Â. Â. Áàðàíåíêî Ñóïåðîêñèääèñìóòàçà â êëåòêàõ ðàñòåíèé Èíñòèòóò áîòàíèêè èì. Í. Ã. Õîëîäíîãî Íàöèîíàëüíîé àêàäåìèè íàóê Óêðàèíû, Êèåâ; ýëåêòðîííûé àäðåñ: [email protected] Ñóïåðîêñèääèñìóòàçà (ÑÎÄ) ÿâëÿåòñÿ îäíèì èç êëþ÷åâûõ êîìïîíåíòîâ ñèñòåìû çàùèòû êëåòîê è òêàíåé îò îêèñëèòåëüíîé äåñòðóêöèè.  îáçîðå îòìå÷åíà óíèêàëüíîñòü ôåðìåíòà ñðåäè äðóãèõ àíòèîêñèäàíòîâ. Îáîáùåíû äàííûå ëèòåðàòóðû î ëîêàëèçàöèè ÑÎÄ âíóòðè êëåòêè è â àïîïëàñòå, î ðåàêöèè íà âîçäåéñòâèå ðàçëè÷íûõ íåáëàãîïðèÿòíûõ ôàêòîðîâ è ðîëè â óñòîé÷èâîñòè êëåòîê è òêàíåé ðàñòåíèé â óñëîâèÿõ ñòðåññà. Ðàññìîòðåíû âîïðîñû, êàñàþùèåñÿ ðåãóëÿöèè àêòèâíîñòè ôåðìåíòà è ó÷àñòèÿ â ïðîöåññàõ ðåãóëÿöèè àêòèâíûõ ôîðì êèñëîðîäà, èîíîâ êàëüöèÿ, ôèòîãîðìîíîâ, ãëóòàòèîíà è îêñèäà àçîòà. ëåòñÿ â ïðåäåëàõ 32—34 êÄà (McCord, Fridovich, 1969; Beauchamp, Fridovich, 1973). Êàæäàÿ ìîëåêóëà ôåðìåíòà ñîäåðæèò ïî 2 ã-àòîìà ìåäè è öèíêà â àêòèâíîì öåíòðå. Êðèñòàëëè÷åñêàÿ ñòðóêòóðà ðàñòèòåëüíîé CuZnÑÎÄ ãîìîëîãè÷íà òàêîâîé èç êëåòîê æèâîòíûõ: êàæäàÿ ñóáúåäèíèöà ôåðìåíòà èìååò ñòðóêòóðó áî÷îíêà (áåòà-áàððåëÿ) (Kitagawa et al., 1991). Îòëè÷èòåëüíîé îñîáåííîñòüþ ðàñòèòåëüíîé ÑÎÄ ÿâëÿåòñÿ ìíîæåñòâåííîñòü èçîçèìîâ ðàçíûõ ôîðì ÑÎÄ, ÷òî íå óäàëîñü îáíàðóæèòü àâòîðó â êëåòêàõ æèâîòíûõ. Òàê, â êëåòêàõ ëèñòüåâ êóêóðóçû îáíàðóæåíî 9 èçîçèìîâ ÑÎÄ: 4 CuZnÑÎÄ â öèòîïëàçìå, 1 CuZnÑÎÄ â õëîðîïëàñòàõ è 4 MnÑÎÄ â ìèòîõîíäðèÿõ (Zhu, Scandalios, 1994). Êîëè÷åñòâî èçîçèìîâ êîëåáëåòñÿ îò îäíîãî âèäà ðàñòåíèé ê äðóãîìó (Scandalios, 1997; Lee et al., 2001). CuZnÑÎÄ îòëè÷àåòñÿ ìîëåêóëÿðíûìè ñâîéñòâàìè îò äâóõ äðóãèõ èçîôîðì — FeÑÎÄ è MnÑÎÄ (ñì. òàáëèöó), òîãäà êàê äâå ïîñëåäíèå ïî ìíîãèì ñâîéñòâàì ãîìîëîãè÷íû òàêîâûì, âûäåëåííûì íå òîëüêî èç ðàçëè÷íûõ ôîðì ðàñòåíèé, íî è èç äðóãèõ èñòî÷íèêîâ (Yost, Fridovich, 1973; Parker et al., 1987). Âñå òðè èçîôîðìû îáúåäèíÿåò ôóíêöèÿ äèñìóòàöèè ñóïåðîêñèäíûõ ðàäèêàëîâ.  ïîñëåäóþùèõ ðàçäåëàõ áóäóò ïðèâåäåíû äàííûå ëèòåðàòóðû î ñòðóêòóðå è ôóíêöèè ÑÎÄ, ëîêàëèçàöèè, ðåàêöèè íà âîçäåéñòâèå ñòðåññîâûõ ôàêòîðîâ, à òàêæå ðåãóëÿöèè àêòèâíîñòè â êëåòêàõ ðàñòåíèé. Àíòèîêñèäàíòíûé ôåðìåíò ñóïåðîêñèääèñìóòàçà (ÑÎÄ; ÊÔ 1.15.1.1) áûë îáíàðóæåí â êîíöå 1930-õ ãîäîâ Ìàííîì è Êåèëèíîì (Mann, Keilin, 1938) êàê ìåäüñîäåðæàùèé áåëîê è íàçâàí ãåìîêóïðåèíîì, à çàòåì ýðèòðîêóïðåèíîì. Ïðåäïîëàãàëè, ÷òî áèîëîãè÷åñêàÿ ðîëü ýòîãî áåëêà çàêëþ÷àëàñü â çàïàñàíèè èîíîâ ìåäè. È òîëüêî â 1969 ã. Ìàê-Êîðäîì è Ôðèäîâè÷åì (McCord, Fridovich, 1969) áûëî îáíàðóæåíî, ÷òî ãåìîêóïðåèí ÿâëÿåòñÿ ôåðìåíòîì, êîòîðûé êàòàëèçèðóåò ðåàêöèþ äèñìóòàöèè ñóïåðîêñèäíûõ ðàäèêàëîâ ( O•2 – ). Íîâûé ôåðìåíò ïðèîáðåë íàçâàíèå ñóïåðîêñèääèñìóòàçû.  1970-å ãîäû èç Escherichia coli áûëè âûäåëåíû ôåðìåíòû ñ àíàëîãè÷íîé ôóíêöèåé, íî âìåñòî èîíîâ ìåäè è öèíêà â àêòèâíîì öåíòðå îíè ñîäåðæàëè èîíû æåëåçà (Yost, Fridovich, 1973) èëè ìàðãàíöà (Keele et al., 1970). Òàêèì îáðàçîì, êðîìå CuZn ÑÎÄ îáíàðóæèëîñü ñóùåñòâîâàíèå åùå äâóõ èçîôîðì ÑÎÄ — MnÑÎÄ è FeÑÎÄ. Äàëüíåéøèå èññëåäîâàíèÿ ïîêàçàëè ïðèñóòñòâèå ÑÎÄ â êëåòêàõ æèâûõ îðãàíèçìîâ ðàçíîãî óðîâíÿ îðãàíèçàöèè: ðàñòåíèé (Beauchamp, Fridovich, 1973), ÷åëîâåêà (Nyman, 1960), æèâîòíûõ (McCord, Fridovich, 1969), ìèêðîîðãàíèçìîâ — ãðèáîâ (Rapp et al., 1973), áàêòåðèé (Keele et al., 1970) è äð. Öåëü íàñòîÿùåãî îáçîðà — îáîáùèòü äàííûå ëèòåðàòóðû, êàñàþùèåñÿ ðàçëè÷íûõ ñòîðîí èçó÷åíèÿ ÑÎÄ â êëåòêàõ ðàñòåíèé. Õàðàêòåðíîé îñîáåííîñòüþ êëåòîê ðàñòåíèé, îòëè÷àþùèõ èõ îò êëåòîê äðóãèõ îðãàíèçìîâ, ÿâëÿåòñÿ íàëè÷èå âñåõ òðåõ èçîôîðì.  êëåòêàõ æèâîòíûõ, ãäå ôåðìåíò áûë âïåðâûå îáíàðóæåí, ïðèñóòñòâóþò òîëüêî CuZnÑÎÄ è MnÑÎÄ (Wanders, Denis, 1992), à â êëåòêàõ ïðîêàðèîò — FeÑÎÄ è MnÑÎÄ (Keele et al., 1970; Yost, Fridovich, 1973). Äàííûå ëèòåðàòóðû óêàçûâàþò íà áîëüøîå ñõîäñòâî ìîëåêóëÿðíûõ ñâîéñòâ ðàñòèòåëüíîé CuZnÑÎÄ ñ òàêîâîé, îáíàðóæåííîé â êëåòêàõ æèâîòíûõ è ÷åëîâåêà (Nyman, 1960; McCord, Fridovich, 1969; Beauchamp, Fridovich, 1973). Ìîëåêóëà CuZnÑÎÄ ðàñòèòåëüíîãî è æèâîòíîãî ïðîèñõîæäåíèÿ ÿâëÿåòñÿ äèìåðîì, ñîñòîÿùèì èç äâóõ ðàâíîãî ðàçìåðà ñóáúåäèíèö, ñâÿçàííûõ íåêîâàëåíòíî; ìîë. ìàññà èçîôîðìû êîëåá- Ñòðóêòóðà è ôóíêöèè ÑÎÄ ÑÎÄ êàòàëèçèðóåò äèñïðîïîðöèîíèðîâàíèå ñóïåðîêñèäíûõ àíèîí-ðàäèêàëîâ äî ìîëåêóëÿðíîãî êèñëîðîäà è ïåðîêñèäà âîäîðîäà (McCord, Fridovich, 1969): •– ÑÎÄ 2O2 + 2H+ ⎯⎯⎯→ H2 O2 + O2 . Ìåõàíèçì äåéñòâèÿ ÑÎÄ çàêëþ÷àåòñÿ â ïîñëåäîâàòåëüíîì âîññòàíîâëåíèè è îêèñëåíèè ñóïåðîêñèäíûìè 465 Â. Â. Áàðàíåíêî 466 Õàðàêòåðèñòèêà è ëîêàëèçàöèÿ èçîôîðì ÑÎÄ â êëåòêàõ ðàñòåíèé ÑÎÄ Õàðàêòåðèñòèêà ÑÎÄ Ëîêàëèçàöèÿ â êëåòêàõ ðàñòåíèé CuZnÑÎÄ Ãîìîäèìåð (33 êÄà) (Christov, Bakardjieva, 1999); â àêòèâíîì öåíòðå ñîäåðæèòñÿ ïî 2 ã-àòîìà ìåäè (Cu2+) è öèíêà (Zn2+) (Bannister et al., 1991) MnÑÎÄ Ãîìîäèìåð (46 êÄà) èëè ãîìîòåòðàìåð (92 êÄà) (Palma et al., 1998); â àêòèâíîì öåíòðå ñîäåðæèòñÿ 2 èëè 4 ã-àòîìà ìàðãàíöà (Mn3+) FeÑÎÄ Ãîìîäèìåð (36—46 êÄà) — â õëîðîïëàñòàõ; Õëîðîïëàñòû (Gomez et al., 2003/4); öèòîïëàçìà êëóáåíüêîâ íåêîòîðûõ áîáîâûõ ñîäåðæàíèå æåëåçà (Fe3+) â àêòèâíîì öåíòðå âàðüèðóåò îò 1 äî 2 ã-àòîìîâ (Salin, (Moran et al., 2003) 1987) è 54 êÄà — â öèòîïëàçìå êëóáåíüêîâ áîáîâûõ (Moran et al., 2003); â àêòèâíîì öåíòðå ñîäåðæèòñÿ 2 ã-àòîìà æåëåçà àíèîí-ðàäèêàëàìè ìåòàëëà (Me) àêòèâíîãî öåíòðà ôåðìåíòà (Asada, 1996): ÑÎÄ-Men+ + O•2 – → ÑÎÄ-Me(n–1)+ + O2, ÑÎÄ-Me(n–1)+ + O•2 – + 2H+ → ÑÎÄ-Men+ + H2O2. •– Ñêîðîñòü âçàèìîäåéñòâèÿ ÑÎÄ ñ O2 â çíà÷èòåëüíîé ñòåïåíè îïðåäåëÿåòñÿ âÿçêîñòüþ ìåìáðàí (Asada, 1996). •– Äèñìóòàöèÿ O2 ìîæåò ïðîèñõîäèòü ñïîíòàííî áåç ó÷àñòèÿ ÑÎÄ. Ñêîðîñòü ñïîíòàííîé äèñìóòàöèè 2$105 Ì–1/ñ–1 ïðè pH 7.0, òîãäà êàê â ïðèñóòñòâèè ÑÎÄ — 2$109 Ì–1/ñ–1, ò. å. ïðèáëèçèòåëüíî â 104 ðàç áûñòðåå (Ogawa et al., 1996). Èçó÷åíèþ ÑÎÄ óäåëÿåòñÿ ìíîãî âíèìàíèÿ, ïîñêîëüêó åé îòâîäèòñÿ âàæíàÿ ðîëü â çàùèòå êëåòîê è òêàíåé îò îêèñëèòåëüíîé äåñòðóêöèè. Ñóïåðîêñèäíûå ðàäèêàëû — ïåðâè÷íûå ïðîäóêòû îäíîýëåêòðîííîãî âîññòàíîâëåíèÿ ìîëåêóëÿðíîãî êèñëîðîäà — ÿâëÿþòñÿ èñòî÷íèêîì îáðàçîâàíèÿ äðóãèõ, â òîì ÷èñëå è áîëåå ðåàêöèîííîñïîñîáíûõ, ÀÔÊ (Ìåðçëÿê, 1989). Ïåðîêñèä âîäîðîäà, ãèäðîêñèëüíûå è ãèäðîïåðåêèñíûå ðàäèêàëû, ñèíãëåòíûé êèñëîðîä è ïåðîêñèíèòðèò ÿâëÿþòñÿ ïðîäóêòàìè ïðåâðà- Ñõåìàòè÷åñêîå èçîáðàæåíèå ðàñïîëîæåíèÿ CuZnÑÎÄ â õëîðîïëàñòàõ øïèíàòà (Ogawa et al., 1995). Èñïîëüçîâàíèå ìåòêè èììóííîãî çîëîòà ïîêàçàëî, ÷òî îêîëî 70 % CuZnÑÎÄ ïðèêðåïëåíî ê ñòðîìàëüíîé ïîâåðõíîñòè òèëàêîèäîâ õëîðîïëàñòîâ øïèíàòà. Schematic representation of CuZnSOD localization in spinach chloroplasts (Ogawa et al., 1995). Immunogold labeling indicates that over 70 % of CuZnSOD attached to stroma-faced thylakoid membranes. Õëîðîïëàñòû (Ogawa et al., 1995); ìèòîõîíäðèè (Kuzniak, Sklodowska, 2004); ïåðîêñèñîìû (Corpas et al., 1998); öèòîïëàçìà (Hernandez et al., 1999); àïîïëàñò (Ogawa et al., 1997) Ìèòîõîíäðèè (Kuzniak, Sklodowska, 2004); ïåðîêñèñîìû (Palma et al., 1998) •– ùåíèÿ ðàäèêàëîâ O2 (Ìåðçëÿê, 1989; Pryor, Squadrito, 1995). Ïîñêîëüêó ãèäðîêñèëüíûå ðàäèêàëû, ñèíãëåòíûé êèñëîðîä è ïåðîêñèíèòðèò àêòèâíî îêèñëÿþò áåëêîâûå ìîëåêóëû, ñïåöèôè÷åñêèõ ôåðìåíòîâ-äåçàêòèâàòîðîâ äàííûõ ÀÔÊ íå ñóùåñòâóåò, óðîâåíü èõ â êëåòêå îïîñðåäîâàííî ðåãóëèðóåòñÿ ÑÎÄ ïóòåì óáîðêè ñóïåðîêñèäíûõ ðàäèêàëîâ — èñòî÷íèêà èõ îáðàçîâàíèÿ. Ïî ýòîé ïðè÷èíå ÑÎÄ ÿâëÿåòñÿ ïåðâè÷íîé ëèíèåé çàùèòû îò îêèñëèòåëüíûõ ïîâðåæäåíèé, îáðûâàÿ îêèñëåíèå êëåòî÷íûõ ìàêðîìîëåêóë åùå íà ñòàäèè èíèöèèðîâàíèÿ. •– Êðîìå ó÷àñòèÿ â îáðàçîâàíèè äðóãèõ ÀÔÊ O2 ìîãóò íåïîñðåäñòâåííî âûçûâàòü îêèñëèòåëüíûå ìîäèôèêàöèè îïðåäåëåííûõ âíóòðèêëåòî÷íûõ ìàêðîìîëåêóë. Ñðåäè ìèøåíåé, ñïîñîáíûõ ê ïðÿìîìó îêèñëåíèþ ñóïåðîêñèäíûìè àíèîí-ðàäèêàëàìè, — áåëêîâûå ìîëåêóëû, ñîäåðæàùèå [FeS]-êëàñòåðû (Palatnik et al., 1999). Ñëåäñòâèåì ýòîãî ÿâëÿþòñÿ èíàêòèâàöèÿ áåëêîâûõ ìîëåêóë è âûñâîáîæäåíèå Fe3+, êîòîðûé â ñâîþ î÷åðåäü ìîæåò âîññòàíàâëèâàòüñÿ êëåòî÷íûìè ðåäóêòàíòàìè, â òîì ÷èñëå è •– ðàäèêàëàìè O2 , äî Fe2+ è çàòåì ïðèíèìàòü ó÷àñòèå â ðåàêöèè Ôåíòîíà ñ îáðàçîâàíèåì ãèäðîêñèëüíûõ ðàäèêàëîâ. Òàêèì îáðàçîì, ñóïåðîêñèäíûå àíèîí-ðàäèêàëû ìîãóò âûçûâàòü ïðÿìûå ïîâðåæäàþùèå ýôôåêòû, à òàêæå áûòü èñòî÷íèêîì îáðàçîâàíèÿ äðóãèõ, â òîì ÷èñëå è áîëåå òîêñè÷íûõ, ôîðì êèñëîðîäà. Ïîýòîìó êëåòêà íóæäàåòñÿ â ñòðîãîì êîíòðîëå íàä ïðîäóêöèåé è ñâîåâðåìåííûì óäàëåíèåì äàííûõ ðàäèêàëîâ. Èçîôîðìû ÑÎÄ îòëè÷àþòñÿ ðàçíîé ÷óâñòâèòåëüíîñòüþ ê èíãèáèòîðàì CN– è H2O2. Òàê, CuZnÑÎÄ èíãèáèðóåòñÿ CN– è H2O2, FeÑÎÄ — òîëüêî H2O2, à MnÑÎÄ íåâîñïðèèì÷èâà ê îáîèì èíãèáèòîðàì (Bowler et al., 1992). Âñå îõàðàêòåðèçîâàííûå CuZnÑÎÄ ÿâëÿþòñÿ ãëàâíûì îáðàçîì ãîìîäèìåðàìè, ñîñòîÿùèìè èç äâóõ ñóáúåäèíèö ïî 16.5 êÄà êàæäàÿ (Bueno, Del Rio, 1992; Christov, Bakardjieva, 1999) (ñì. òàáëèöó). Ìîëåêóëà FeÑÎÄ — òàêæå ãîìîäèìåð, èìåþùèé ìîë. ìàññó 36—46 êÄà â õëîðîïëàñòàõ (Salin, 1987) è 54 êÄà — â öèòîçîëå êëóáåíüêîâ áîáîâûõ (Moran et al., 2003). MnÑÎÄ èìååò ìîë. ìàññó 46 èëè 92 êÄà è ñîñòîèò ñîîòâåòñòâåííî èç 2 èëè 4 îäèíàêîâîãî ðàçìåðà ñóáúåäèíèö (Palma et al., 1998). Èçîôîðìû ÑÎÄ ðàçëè÷àþòñÿ íå òîëüêî ìîëåêóëÿðíîé ìàññîé è ÷óâñòâèòåëüíîñòüþ ê èíãèáèòîðàì, íî òàêæå ëîêàëèçàöèåé â êëåòêàõ ðàñòåíèé. Ñóïåðîêñèääèñìóòàçà â êëåòêàõ ðàñòåíèé Ëîêàëèçàöèÿ ÑÎÄ Ôåðìåíò ïðèñóòñòâóåò â êëåòêàõ ðàñòåíèé òàì, ãäå ïðîèñõîäÿò îêèñëèòåëüíî-âîññòàíîâèòåëüíûå ïðîöåññû, ò. å. ïðàêòè÷åñêè âî âñåõ åå êîìïàðòìåíòàõ, à òàêæå â àïîïëàñòå. Ñðàâíåíèå äàííûõ î ëîêàëèçàöèè ðàçíûõ ôîðì ÑÎÄ ïîêàçûâàåò, ÷òî íàèáîëåå èçîáèëüíîé â êëåòêàõ ðàñòåíèé ÿâëÿåòñÿ CuZnÑÎÄ. Îíà îáíàðóæåíà âî âñåõ âíóòðèêëåòî÷íûõ êîìïàðòìåíòàõ — â öèòîçîëå (Hernandez et al., 1999; Hurst et al., 2002), õëîðîïëàñòàõ (Ogawa et al., 1995; Hernandez et al., 1999), ìèòîõîíäðèÿõ (Kuzniak, Slkodowska, 2004), ïåðîêñèñîìàõ (Corpas et al., 1998), à òàêæå â àïîïëàñòå (Ogawa et al., 1997) (ñì. òàáëèöó). ×òî êàñàåòñÿ MnÑÎÄ è FeÑÎÄ, îíè îáíàðóæåíû ëèøü â îïðåäåëåííûõ îðãàíåëëàõ.  ÷àñòíîñòè, MnÑÎÄ ðàñïîëîæåíà â ìèòîõîíäðèÿõ (Kuzniak, Slkodowska, 2004) è ïåðîêñèñîìàõ (Palma et al., 1998), à FeÑÎÄ — â õëîðîïëàñòàõ (Navari-Izzo et al., 1998; Gomez et al., 2003/4) è öèòîïëàçìå êëóáåíüêîâ íåêîòîðûõ áîáîâûõ (Moran et al., 2003). Ðàññìîòðèì áîëåå ïîäðîáíî ëîêàëèçàöèþ èçîôîðì ÑÎÄ â êëåòêàõ ðàñòåíèé. Öèòîçîëüíàÿ ôîðìà CuZnÑÎÄ îáíàðóæåíà âîçëå èëè íà òîíîïëàñòå, à òàêæå â ñàìîì ÿäðå, ÷òî óêàçûâàåò íà îáðàçîâàíèå ñóïåðîêñèäíûõ ðàäèêàëîâ âíóòðè ÿäðà (Ogawa et al., 1996). Ïðåäïîëàãàþò, ÷òî â ÿäðî ôåðìåíòà ïîïàäàåò ÷åðåç ÿäåðíûå ïîðû.  ÿäðå ÑÎÄ (äî 80 %) ñâÿçàíà ñ ÄÍÊ-ôèëàìåíòàìè, çàùèùàÿ èõ îò îêèñëèòåëüíûõ ïîâðåæäåíèé (Ogawa et al., 1996). Äàííàÿ èçîôîðìà îáíàðóæåíà òàêæå âîçëå èëè íà öèòîïëàçìàòè÷åñêîé ìåìáðàíå (Ogawa et al., 1996).  õëîðîïëàñòàõ CuZnÑÎÄ ëîêàëèçîâàíà â ìåìáðàíàõ òèëàêîèäîâ è ñòðîìå (Ogawa et al., 1995; Gomez et al., 2003/4).  ÷àñòíîñòè, îêîëî 70 % CuZnÑÎÄ ïðèêðåïëåíî ê ñòðîìàëüíîé ïîâåðõíîñòè ìåìáðàí òèëàêîèäîâ, ãäå ðàñïîëîæåí êîìïëåêñ ôîòîñèñòåìû I (Ogawa et al., 1995). Îòìå÷åíî, ÷òî ëîêàëüíàÿ êîíöåíòðàöèÿ ôåðìåíòà â ìåìáðàíàõ òèëàêîèäîâ ñîñòàâëÿåò îêîëî 1 ìÌ, òîãäà êàê â ñòðîìå — îêîëî 20 ìêÌ (Ogawa et al., 1995). Òàêèì îáðàçîì, áîëüøåå êîëè÷åñòâî ÑÎÄ ïðèêðåïëåíî ê òèëàêîèäíûì ìåìáðàíàì, è ýòî ñâèäåòåëüñòâóåò î òîì, ÷òî ïðîäóêöèÿ â íèõ ñóïåðîêñèäíûõ ðàäèêàëîâ âûøå ïî ñðàâíåíèþ ñî ñòðîìîé. Ôåðìåíò îáíàðóæåí òàêæå âî âíóòðèòèëàêîèäíîì ïðîñòðàíñòâå õëîðîïëàñòîâ (îêîëî 4 % õëîðîïëàñòíîé CuZnÑÎÄ) (Hayakawa et al., 1984). Ïîñêîëüêó îñíîâíîå êîëè÷åñòâî CuZnÑÎÄ â êëåòêàõ ëèñòüåâ ðàñòåíèé, êàê ñâèäåòåëüñòâóþò äàííûå ëèòåðàòóðû, ëîêàëèçîâàíî â õëîðîïëàñòàõ (Asada, 1996), î÷åâèäíî, ÷òî ïîñëåäíèå ÿâëÿþòñÿ âàæíûì èñòî÷íèêîì ñóïåðîêñèäíûõ ðàäèêàëîâ â êëåòêå. Êðîìå õëîðîïëàñòîâ CuZnÑÎÄ îáíàðóæåíà â ìàòðèêñå ïåðîêñèñîì (Sandalio, Del Rio, 1987; Corpas et al., 1998), ãäå îíà ÿâëÿåòñÿ òàêæå ïðåîáëàäàþùåé èçîôîðìîé ÑÎÄ. Íà äîëþ ïåðîêñèñîìíîé CuZnÑÎÄ ïðèõîäèòñÿ îêîëî 18 % îáùåé àêòèâíîñòè ÑÎÄ â êëåòêàõ ðàñòåíèé (Sandalio, Del Rio, 1987).  àïîïëàñòå äàííàÿ èçîôîðìà ïðèíèìàåò ó÷àñòèå â ëèãíèôèêàöèè êëåòî÷íûõ ñòåíîê è çàùèòå êëåòîê è òêàíåé ðàñòåíèé îò ïàòîãåíîâ (Ogawa et al., 1997; Shinkel et al., 2001). MnÑÎÄ îáíàðóæåíà â ìàòðèêñå ìèòîõîíäðèé è ïåðîêñèñîì (Del Rio et al., 2003; Moller, 2001). Îòìå÷åíà çíà÷èòåëüíàÿ ãîìîëîãèÿ àìèíîêèñëîòíûõ ïîñëåäîâàòåëüíîñòåé ôåðìåíòà â ìèòîõîíäðèÿõ ñ òàêîâîé â ïåðîêñèñîìàõ (Del Rio et al., 2003). FeÑÎÄ â êëåòêàõ ðàñòåíèé ðàñïîëîæåíà ãëàâíûì îáðàçîì â õëîðîïëàñòàõ — êàê â ñòðîìå, òàê è íà ìåìáðàíàõ òèëàêîèäîâ (Navarri-Izzo et al., 1998; Gomez et al., 467 2003/4). Êðîìå õëîðîïëàñòîâ îáíàðóæåíà ëîêàëèçàöèÿ ôåðìåíòà â íåôîòîñèíòåçèðóþùèõ îðãàíåëëàõ è òêàíÿõ: â ïåðîêñèñîìàõ ëèñòüåâ Lycopersicon esculentum (Mittova et al., 2003), ïåðîêñèñîìàõ ëåïåñòêîâ ãâîçäèêè (Droillard, Paulin, 1990), à òàêæå â öèòîçîëå êëóáåíüêîâ íåêîòîðûõ áîáîâûõ — êëåâåðà, ñîè è ôàñîëè (Moran et al., 2003). Îäíàêî íå ó âñåõ áîáîâûõ îáíàðóæåí ôåðìåíò â öèòîçîëå êëóáåíüêîâ: ó ëþöåðíû è ãîðîõà îí ëîêàëèçîâàí èñêëþ÷èòåëüíî â õëîðîïëàñòàõ (Moran et al., 2003). Òàêèì îáðàçîì, ñóùåñòâóåò íåñêîëüêî òèïîâ FeÑÎÄ â êëåòêàõ ðàñòåíèé. Ïîòðåáíîñòü êëåòîê ðàñòåíèé â èçîôîðìàõ ÑÎÄ, èìåþùèõ ðàçíûå õàðàêòåðèñòèêè, î÷åâèäíî, îáúÿñíÿåòñÿ íåîáõîäèìîñòüþ áîëåå ýôôåêòèâíîé çàùèòû îò îêèñëèòåëüíîé äåñòðóêöèè. Àêòèâíîñòü ÑÎÄ â óñëîâèÿõ äåéñòâèÿ íåáëàãîïðèÿòíûõ ôàêòîðîâ  îáû÷íûõ óñëîâèÿõ ñóùåñòâîâàíèÿ •ïîääåðæèâàåò– ñÿ áàëàíñ ìåæäó ïðîäóêöèåé ðàäèêàëîâ O2 è èõ ñâîåâðåìåííûì óäàëåíèåì. Ïðè äåéñòâèè íåáëàãîïðèÿòíûõ ôàêòîðîâ óâåëè÷èâàåòñÿ îáðàçîâàíèå àêòèâíûõ ôîðì êèñëîðîäà, â òîì ÷èñëå è ðàäèêàëîâ ñóïåðîêñèäà (Edreva et al., 1998; Kami*nska-Ro¿ek, Pukacki, 2004). Àêòèâíîñòü ÑÎÄ ïðè ýòîì èçìåíÿåòñÿ ðàçíîíàïðàâëåííî; â îäíèõ ñëó÷àÿõ îòìå÷åíî åå óâåëè÷åíèå, â äðóãèõ — ñíèæåíèå, ÷òî çàâèñèò îò íàïðÿæåííîñòè äåéñòâèÿ ñòðåññîâîãî ôàêòîðà (èíòåíñèâíîñòè è äëèòåëüíîñòè âîçäåéñòâèÿ), à òàêæå îò âîñïðèèì÷èâîñòè îðãàíèçìà, ñòàäèè ðàçâèòèÿ ðàñòåíèé è äð. Óâåëè÷åíèå àêòèâíîñòè ôåðìåíòà îòìå÷åíî â óñëîâèÿõ âîäíîãî äåôèöèòà (Iturbe-Ormaetxe et al., 1998; Kami*nska-Ro¿ek, Pukacki, 2004) è ïåðåóâëàæíåíèÿ ïî÷âû (Êàëàøíèêîâ è äð., 1994), ïðè òåïëîâîì øîêå (Êóðãàíîâà è äð., 1997; Kang, Saltveit, 2001) è îõëàæäåíèè (Kuk et al., 2003), ñîëåâîì ñòðåññå (Lee et al., 2001; Hurst et al., 2002), ïðè ÓÔ-îáëó÷åíèè (Schmitz-Eiberger, Noga, 2001), èíòåíñèâíîì îñâåùåíèè (Logan et al., 1998), îáðàáîòêå ðàñòåíèé îçîíîì (Alonso et al., 2001), òÿæåëûìè ìåòàëëàìè (Garcia et al., 1999; Skorzynska-Polit et al., 2003/4), àáñöèçîâîé êèñëîòîé (Jiang, Zhang, 2001), ïðè èíîêóëÿöèè ïàòîãåíàìè (Babithaa et al., 2002; Kuzniak et al., 2004). Òàêèì îáðàçîì, ðàçíîîáðàçíûå íåáëàãîïðèÿòíûå âîçäåéñòâèÿ, äàæå ïðîòèâîïîëîæíûå ïî ñâîåé ïðèðîäå (çàñóõà—ïåðåóâëàæíåíèå), ìîãóò ïðèâîäèòü ê àêòèâàöèè ÑÎÄ. Óâåëè÷åíèå àêòèâíîñòè ôåðìåíòà ïðè ðàçëè÷íûõ ñòðåññîâûõ âîçäåéñòâèÿõ ìîæåò áûòü îáóñëîâëåíî àêòèâàöèåé åãî ëàòåíòíûõ ôîðì è(èëè) ñèíòåçîì íîâûõ ìîëåêóë ôåðìåíòà. Òàê, îäíîâðåìåííîå óâåëè÷åíèå àêòèâíîñòè ÑÎÄ è êîëè÷åñòâà ñîîòâåòñòâóþùèõ áåëêîâ îòìå÷åíî ïðè ñîëåâîì ñòðåññå â õëîðîïëàñòàõ ãîðîõà (Gomez et al., 2003/4) è ëèñòüÿõ òîëåðàíòíîãî ñîðòà Lycopersicon pennellii (Mittova et al., 2003), õëîðîïëàñòàõ ïøåíèöû ïðè îáðàáîòêå ðàñòåíèé ðàñòâîðîì ìåäè (Navari-Izzo et al., 1998), ÷òî ñâèäåòåëüñòâóåò îá óâåëè÷åíèè ñèíòåçà ôåðìåíòà â óñëîâèÿõ äåéñòâèÿ ñòðåññîâîãî ôàêòîðà. Àêòèâàöèÿ ÑÎÄ ïðè íåáëàãîïðèÿòíûõ âîçäåéñòâèÿõ ÿâëÿåòñÿ îòâåòîì íà óâåëè÷åíèå ïðîäóêöèè ðàäèêàëîâ ñóïåðîêñèäà â ýòèõ óñëîâèÿõ, ÷òî îáåñïå÷èâàåò çàùèòó êëåòîê è òêàíåé ðàñòåíèé îò îêèñëèòåëüíûõ ïîâðåæäåíèé. Èçó÷åíèå ïîâåäåíèÿ ôåðìåíòà â ðàñòåíèÿõ, ðàçëè÷àþùèõñÿ ïî óñòîé÷èâîñòè ê òîìó èëè èíîìó âîçäåéñòâèþ, ïîêàçûâàåò, ÷òî óñòîé÷èâûå ðàñòåíèÿ ïî ñðàâíåíèþ 468 Â. Â. Áàðàíåíêî ñ âîñïðèèì÷èâûìè õàðàêòåðèçóþòñÿ áîëåå âûñîêèìè àêòèâíîñòÿìè ÑÎÄ è ìåíåå âûðàæåííûìè îêèñëèòåëüíûìè ïîâðåæäåíèÿìè (Babithaa et al., 2002; Mittova et al., 2003; Wu et al., 2003). Òàê, â óñëîâèÿõ ñîëåâîãî ñòðåññà îòìå÷åíî óâåëè÷åíèå àêòèâíîñòè ÑÎÄ â ìèòîõîíäðèÿõ è ïåðîêñèñîìàõ ëèñòüåâ òîëåðàíòíîãî ñîðòà òîìàòîâ Lycopersicon pennellii, òîãäà êàê ó ðàñòåíèé îáû÷íîãî ñîðòà (Lycopersicon esculentum) ïðîèñõîäèëî ñíèæåíèå àêòèâíîñòè ôåðìåíòà â ìèòîõîíäðèÿõ, à â ïåðîêñèñîìàõ èçìåíåíèÿ îòñóòñòâîâàëè (Mittova et al., 2003). Ïðè ýòîì ïîêàçàòåëè îêèñëèòåëüíîãî ñòðåññà (íàêîïëåíèå ïåðîêñèäà âîäîðîäà è èíòåíñèâíîñòü ïåðîêñèäíîãî îêèñëåíèÿ ëèïèäîâ) áûëè çíà÷èòåëüíåå âûðàæåíû ó îáû÷íûõ ðàñòåíèé, òîãäà êàê ó òîëåðàíòíîãî ñîðòà èìåëî ìåñòî äàæå ñíèæåíèå óðîâíÿ îêèñëåíèÿ â ïåðîêñèñîìàõ (Mittova et al., 2003). Òàêèì îáðàçîì, óñòîé÷èâûå ðàñòåíèÿ èìåþò áîëåå ýôôåêòèâíóþ ñèñòåìó çàùèòû, ÷òî îáåñïå÷èâàåò âîçìîæíîñòü ôóíêöèîíèðîâàíèÿ â óñëîâèÿõ ñòðåññà. Òðàíñãåííûå ðàñòåíèÿ, èìåþùèå ïîâûøåííûå óðîâíè àíòèîêñèäàíòîâ, â òîì ÷èñëå è ÑÎÄ, òàêæå ÿâëÿþòñÿ áîëåå óñòîé÷èâûìè ê âîçäåéñòâèþ íåáëàãîïðèÿòíûõ ôàêòîðîâ ïî ñðàâíåíèþ ñ îáû÷íûìè ðàñòåíèÿìè (Van Camp et al., 1996a; Van Breusegem et al., 1999; Basu et al., 2001; Gao et al., 2003). Òàê, â òðàíñãåííûõ ðàñòåíèÿõ Brassica napus êîëè÷åñòâî òðàíñêðèïòîâ è îáùàÿ àêòèâíîñòü ÑÎÄ áûëè âûøå ïî ñðàâíåíèþ ñ òàêîâûìè â êëåòêàõ îáû÷íûõ ðàñòåíèé (Basu et al., 2001). Ïðè îáðàáîòêå àëþìèíèåì ó îáîèõ òèïîâ ðàñòåíèé îòìå÷åíî èíãèáèðîâàíèå ðîñòà êîðíåé è óâåëè÷åíèå óðîâíÿ ïåðîêñèäíîãî îêèñëåíèÿ ëèïèäîâ, îäíàêî ýòè ïîêàçàòåëè áûëè ìåíåå âûðàæåíû ó òðàíñãåííûõ ðàñòåíèé (Basu et al., 2001).  êëåòêàõ ðàñòåíèé-ìóòàíòîâ, äåôèöèòíûõ ïî ãåíó ÑÎÄ, ïðè èíîêóëÿöèè ïàòîãåíàìè òàêæå îòìå÷åíû çíà÷èòåëüíûå ïîâðåæäåíèÿ ïî ñðàâíåíèþ ñ îáû÷íûìè ðàñòåíèÿìè (Rolke et al., 2004). Òàêèì îáðàçîì, ëèòåðàòóðíûå äàííûå ñâèäåòåëüñòâóþò î ñóùåñòâîâàíèè òåñíîé ñâÿçè ìåæäó óñòîé÷èâîñòüþ ðàñòåíèé ê òîìó èëè èíîìó âîçäåéñòâèþ è ïîâûøåííûìè óðîâíÿìè èëè àêòèâíîñòÿìè êîìïîíåíòîâ ñèñòåìû çàùèòû, â òîì ÷èñëå è ÑÎÄ, ò. å. ñ ïîâûøåííîé ñïîñîáíîñòüþ êëåòîê è òêàíåé óáèðàòü àêòèâíûå ôîðìû êèñëîðîäà. Îäíàêî ïðè äîñòèæåíèè îïðåäåëåííîãî óðîâíÿ îêèñëèòåëüíîãî ñòðåññà ïðîèñõîäèò ñíèæåíèå àêòèâíîñòè ÑÎÄ. Íàïðèìåð, â ëèñòüÿõ ïøåíèöû â óñëîâèÿõ çàñóõè âíà÷àëå îòìå÷åíà àêòèâàöèÿ ôåðìåíòà, çàòåì ñ óâåëè÷åíèåì äëèòåëüíîñòè âîçäåéñòâèÿ ïðîèñõîäèëî ñíèæåíèå àêòèâíîñòè (Zhang, Kirkham, 1994). Òàêàÿ æå òåíäåíöèÿ îòìå÷åíà ïðè óâåëè÷åíèè íå òîëüêî äëèòåëüíîñòè âîçäåéñòâèÿ (Jiang, Huang, 2001), íî è åãî èíòåíñèâíîñòè: ïðè âîäíîì äåôèöèòå (Iturbe-Ormaetxe et al., 1998; Fu, Huang, 2001), ïåðåóâëàæíåíèè (Êàëàøíèêîâ è äð., 1999), ñîëåâîì ñòðåññå (Santos et al., 2001), îáðàáîòêå àáñöèçîâîé êèñëîòîé (Jiang, Zhang, 2001) è òÿæåëûìè ìåòàëëàìè (Garcia et al., 1999), ôóìèãàöèè HF (Ãðèøêî, Ñûùèêîâ, 1999) è äð. Ñíèæåíèå àêòèâíîñòè ôåðìåíòà ìîæåò ïðîèñõîäèòü è áåç åãî ïðåäâàðèòåëüíîé àêòèâàöèè â ñëó÷àå äîâîëüíî èíòåíñèâíîãî âîçäåéñòâèÿ, ÷òî îòìå÷åíî ïðè îáðàáîòêå ðàñòåíèé òÿæåëûìè ìåòàëëàìè (Mishra, Shoudhuri, 1999; Sandalio et al., 2001), UV-C-îáëó÷åíèÿ (Barka, 2001), ñîëåâîì ñòðåññå (Muthukumarasamy et al., 2000; Santos et al., 2001), îõëàæäåíèÿ (Michaeli et al., 2001), òåïëîâîì ñòðåññå (Liu, Huang, 2000), çàòîïëåíèè (Êàëàøíèêîâ è äð., 1999), èíîêóëÿöèè ïàòîãåíàìè (Hernandez et al., 2004) è äð. Ïîñòåïåííîå ñíèæåíèå àêòèâíîñòè ÑÎÄ îòìå÷åíî â êëåòêàõ è òêàíÿõ ðàñòåíèé ïðè èõ ñòàðåíèè (Abarca et al., 2001; Sairam et al., 2003). Ïðè÷èíû ñíèæå- íèÿ àêòèâíîñòè ÑÎÄ ìîãóò áûòü ðàçíîîáðàçíûìè, íàïðèìåð èñòîùåíèå ïóëà ôåðìåíòîâ óñèëåííûì åãî •– ðàñõîäîâàíèåì íà ãàøåíèå ðàäèêàëîâ O2 . Êðîìå òîãî, ïîñêîëüêó àêòèâíîñòü ÑÎÄ ÿâëÿåòñÿ ðåçóëüòàòîì êàê åå ñèíòåçà, òàê è äåãðàäàöèè, óìåíüøåíèå àêòèâíîñòè ìîæåò áûòü ñëåäñòâèåì ñíèæåíèÿ ñèíòåçà è(èëè) ïîâûøåíèÿ äåãðàäàöèè ìîëåêóë ÑÎÄ.  èíàêòèâàöèè è äåãðàäàöèè ÑÎÄ ìîãóò ïðèíèìàòü ó÷àñòèå ÀÔÊ — ãèäðîêñèëüíûå ðàäèêàëû è ïåðîêñèä âîäîðîäà (Casano et al., 1997).  ÷àñòíîñòè, H2O2 ìîæåò âîññòàíàâëèâàòü Cu2+ â àêòèâíîì öåíòðå ôåðìåíòà äî Cu+, êîòîðûé, âçàèìîäåéñòâóÿ ñ íîâîé ìîëåêóëîé ïåðîêñèäà âîäîðîäà, îáðàçóåò Cu2+OH• . Ýòîò ñâÿçàííûé in situ ðàäèêàë OH• âûçûâàåò îêèñëèòåëüíóþ ìîäèôèêàöèþ àìèíîêèñëîòíûõ ïîñëåäîâàòåëüíîñòåé â àêòèâíîì öåíòðå ôåðìåíòà, ÷òî ïðèâîäèò ê åãî èíàêòèâàöèè (Casano et al., 1997). Íå òîëüêî ñâÿçàííûå, íî è ñâîáîäíûå ðàäèêàëû OH• ïîâðåæäàþò ìîëåêóëû ÑÎÄ, âûçûâàÿ èõ ôðàãìåíòàöèþ (Casano et al., 1997). Ïîäòâåðæäåíèåì ó÷àñòèÿ ÀÔÊ â ñíèæåíèè àêòèâíîñòè ÑÎÄ ÿâëÿåòñÿ ðàáîòà Ìóòóêóìàðàñàìè è ñîàâòîðîâ (Muthukumarasamy et al., 2000), â êîòîðîé îòìå÷åíî, ÷òî îáðàáîòêà ðàñòåíèé ðåäèñà ðàñòâîðàìè ïàêëîáóòðàçîëà è òðèàäèìåôîíà, õèìè÷åñêèìè àíòèîêñèäàíòàìè ñïîñîáñòâîâàëà ñîõðàíåíèþ àêòèâíîñòè ÑÎÄ è óëó÷øàëà óñòîé÷èâîñòü ðàñòåíèé ê ñîëåâîìó ñòðåññó. Ñíèæåíèå àêòèâíîñòè ôåðìåíòà ïðè íåáëàãîïðèÿòíûõ âîçäåéñòâèÿõ ñïîñîáñòâóåò äàëüíåéøåìó óâåëè÷åíèþ ïðîäóêöèè ÀÔÊ è ðàçâèòèþ îêèñëèòåëüíûõ ïîâðåæäåíèé êëåòîê è òêàíåé ðàñòåíèé (Jiang, Huang, 2001). Ðåãóëÿöèÿ àêòèâíîñòè ÑÎÄ Ðåãóëÿöèÿ àêòèâíîñòè ÑÎÄ íà óðîâíå ò ð à í ñ ê ð è ï ö è è, ò ð à í ñ ë ÿ ö è è è ï ó ò å ì ï î ñ ò ò ð à íñ ë ÿ ö è î í í î é ì î ä è ô è ê à ö è è. Äîñòàòî÷íî âàæíûì ÿâëÿåòñÿ âîïðîñ îòíîñèòåëüíî ðåãóëÿöèè ÑÎÄ. Ëèòåðàòóðíûå äàííûå ñâèäåòåëüñòâóþò î òîì, ÷òî ðåãóëÿöèÿ àêòèâíîñòè ôåðìåíòà ïðîèñõîäèò íà ðàçíûõ óðîâíÿõ: íà óðîâíå òðàíñêðèïöèè, òðàíñëÿöèè è(èëè) ïóòåì ïîñòòðàíñëÿöèîííîé ìîäèôèêàöèè ìîëåêóë ÑÎÄ.  ÷àñòíîñòè, ïîêàçàíî, ïðè îáðàáîòêå ðàñòåíèé êóêóðóçû ìåòèëâèîëîãåíîì àêòèâàöèÿ ÑÎÄ â ëèñòüÿõ ðàñòåíèé áûëà îáóñëîâëåíà óâåëè÷åíèåì òðàíñêðèïöèè ñîîòâåòñòâóþùèõ ãåíîâ (Scandalios, 1993). Ïàðàëëåëüíîå óâåëè÷åíèå àêòèâíîñòè ÑÎÄ è êîëè÷åñòâà ñîîòâåòñòâóþùèõ òðàíñêðèïòîâ ïðè ñòðåññîâûõ âîçäåéñòâèÿõ îòìå÷åíî è äðóãèìè àâòîðàìè (Casano et al., 1994; Hernandez et al., 2000; Hurst et al., 2002; Del Rio et al., 2003). Îäíàêî íå âñåãäà èçìåíåíèÿ â àêòèâíîñòè ÑÎÄ êîððåëèðóþò ñ ñîîòâåòñòâóþùèìè èçìåíåíèÿìè â êîëè÷åñòâå òðàíñêðèïòîâ (Williamson, Scandalios, 1992; Madamanchi et al., 1994; Slesak et al., 2003). Òàê, ïðè îáðàáîòêå ðàñòåíèé êóêóðóçû öåðêîñïîðèíîì îòìå÷åíî ñíèæåíèå êîëè÷åñòâà òðàíñêðèïòîâ ÑÎÄ â ëèñòüÿõ, îäíàêî îáùàÿ àêòèâíîñòü ôåðìåíòà è êîëè÷åñòâî áåëêà íå èçìåíèëèñü (Williamson, Scandalios, 1992). Òàêæå îáðàáîòêà ðàñòåíèé ãîðîõà SO2 âûçâàëà óâåëè÷åíèå àêòèâíîñòè ôåðìåíòà, îäíàêî êîëè÷åñòâî ñîîòâåòñòâóþùèõ ìàòðè÷íûõ ÐÍÊ (ìÐÍÊ) îñòàëîñü êîíñòàíòíûì, ÷òî ñâèäåòåëüñòâóåò î ñóùåñòâîâàíèè àäàïòèâíûõ ïîñòòðàíñêðèïöèîííûõ ñîáûòèé è(èëè) ñèíòåçå äîïîëíèòåëüíûõ ìîëåêóë ÑÎÄ ñ ìÐÍÊ, êîòîðûå óæå ïðèñóòñòâîâàëè â êëåòêàõ ê ìîìåíòó âîçäåéñòâèÿ (Madamanchi et al., 1994). Äàííûå î ðåãóëÿöèè àêòèâíîñòè ÑÎÄ íà ïîñòòðàíñëÿöèîííîì óðîâíå ïðèâåäåíû â ðàáîòàõ Ñóïåðîêñèääèñìóòàçà â êëåòêàõ ðàñòåíèé Áðîåòòî è ñîàâòîðîâ (Broetto et al., 2002), Äåëü Ðèî è ñîàâòîðîâ (Del Rio et al., 2003) è Ãîìåîç è ñîàâòîðîâ (Gomez et al., 2003/2004). Ïîñêîëüêó ôåðìåíò àêòèâèðóåòñÿ ñóáñòðàòîì (Thompson et al., 1987), àêòèâàöèÿ ìîëåêóë ÑÎÄ ïðè ýòîì, î÷åâèäíî, îáóñëîâëåíà óâåëè÷åíèåì ïðîäóêöèè ñóïåðîêñèäíûõ ðàäèêàëîâ â óñëîâèÿõ ñòðåññà. Òàêèì îáðàçîì, íà ïåðâûõ ýòàïàõ ñòðåññîâîãî âîçäåéñòâèÿ, âåðîÿòíî, ïðîèñõîäèò àêòèâàöèÿ ñóùåñòâóþùèõ ìîëåêóë ÑÎÄ è, âîçìîæíî, ñèíòåç ôåðìåíòà ñ ïðèñóòñòâóþùèõ ìàòðèö (ìÐÍÊ). Åñëè ýòîãî íåäîñòàòî÷íî äëÿ îáåñïå÷åíèÿ àäàïòàöèè ðàñòåíèé, âêëþ÷àåòñÿ ñèíòåç íîâûõ ìÐÍÊ è ìîëåêóë ÑÎÄ, ò. å. â êàæäîì êîíêðåòíîì ñëó÷àå àêòèâíîñòü ôåðìåíòà ðåãóëèðóåòñÿ â çàâèñèìîñòè îò ìåòàáîëè÷åñêèõ ïîòðåáíîñòåé êëåòîê, ÷òî â ñâîþ î÷åðåäü îïðåäåëÿåòñÿ èíòåíñèâíîñòüþ ñòðåññîâîãî âîçäåéñòâèÿ, åãî äëèòåëüíîñòüþ, ÷óâñòâèòåëüíîñòüþ ðàñòåíèé è äð.  í ó ò ð è ê ë å ò î ÷ í û å ì î ë å ê ó ë û è è î í û, î ê àç û â à þ ù è å ð å ã ó ë è ð ó þ ù å å â ë è ÿ í è å í à à ê ò è âí î ñ ò ü Ñ Î Ä è ý ê ñ ï ð å ñ ñ è þ å å ã å í î â. Î÷åíü ìàëî èçâåñòíî î ïóòÿõ ñèãíàëüíîé òðàíñäóêöèè, êîòîðûå ïðèâîäÿò ê èíäóêöèè àíòèîêñèäàíòíîé çàùèòû, â òîì ÷èñëå è ÑÎÄ. Êàê ñâèäåòåëüñòâóþò ëèòåðàòóðíûå äàííûå, ïðåäïîëàãàåìûìè ó÷àñòíèêàìè â öåïè ïåðåäà÷è ñèãíàëîâ, ïðèâîäÿùèõ ê àêòèâàöèè ÑÎÄ è ýêñïðåññèè åå ãåíîâ, ÿâëÿþòñÿ ÀÔÊ (Kardish et al., 1994; Herbette et al., 2003), èîíû êàëüöèÿ (Jiang, Zhang, 2003), îêñèä àçîòà (NO) (Herbette et al., 2003; Neil et al., 2003), ãëóòàòèîí (Herouart et al ., 1993), ôèòîãîðìîíû, â ÷àñòíîñòè ÀÁÊ (Kaminaka et al., 1999; Bellaire et al., 2000), è ñàëèöèëîâàÿ êèñëîòà (Scandalios, 1997; Herbette et al., 2003). Ðàññìîòðèì áîëåå ïîäðîáíî âîçìîæíîå ó÷àñòèå êàæäîãî èç ýòèõ êîìïîíåíòîâ â àêòèâàöèè ÑÎÄ è ðåãóëÿöèè ýêñïðåññèè åå ãåíîâ. ×òî êàñàåòñÿ ÀÔÊ, èçâåñòíî, ÷òî â ïîâûøåííûõ êîëè÷åñòâàõ îíè îêàçûâàþò íå òîëüêî âðåäíîå âîçäåéñòâèå íà êëåòêè è òêàíè, íî òàêæå ÿâëÿþòñÿ ñèãíàëüíûìè ìîëåêóëàìè, ó÷àñòâóþùèìè â àêòèâàöèè çàùèòíûõ ñèñòåì (Foyer et al., 1997; Neill et al., 2002). Ñóùåñòâóåò ïðåäïîëîæåíèå î òîì, ÷òî òàê íàçûâàåìàÿ îêèñëèòåëüíàÿ âñïûøêà — óñèëåííàÿ âíå- èëè âíóòðèêëåòî÷íàÿ ïðîäóêöèÿ ÀÔÊ â 1-å ìèí âîçäåéñòâèÿ — ÿâëÿåòñÿ íà÷àëüíûì ñîáûòèåì â öåïè ïåðåäà÷è ñèãíàëîâ, êîòîðîå çàïóñêàåò (âêëþ÷àåò) ðàáîòó äðóãèõ ìåõàíèçìîâ çàùèòû (Foyer et al., 1997; Lamb, Dixon, 1997). Óâåëè÷åíèå ïðîäóêöèè ÀÔÊ, î÷åâèäíî, èçìåíÿåò ðåäîêñ-ñîñòîÿíèå îïðåäåëåííûõ âíóòðèêëåòî÷íûõ ìàêðîìîëåêóë; èõ îêèñëåíèå èëè âîññòàíîâëåíèå ïðèâîäèò ê àêòèâàöèè èëè èíãèáèðîâàíèþ ïîñëåäóþùèõ ïðîöåññîâ â öåïè ïåðåäà÷è ñèãíàëîâ. Òàê, Ñëåñàê è ñîàâòîðû (Slesak et al., 2003) ïðåäïîëîæèëè, ÷òî ýêñïðåññèÿ ãåíîâ ÑÎÄ â õëîðîïëàñòàõ ðåãóëèðóåòñÿ, õîòÿ áû ÷àñòè÷íî, èçìåíåíèåì ðåäîêñ-ñîñòîÿíèÿ ïåðåíîñ÷èêîâ ýëåêòðîíîâ â ýëåêòðîí-òðàíñïîðòíîé öåïè ôîòîñèíòåòè÷åñêîãî àïïàðàòà. Ðåçóëüòàòû èññëåäîâàíèé Õåðáåòò è ñîàâòîðîâ (Herbette et al., 2003) òàêæå ñâèäåòåëüñòâóþò î òîì, ÷òî ÀÔÊ èíäóöèðóþò ýêñïðåññèþ ãåíîâ ÑÎÄ íà óðîâíå òðàíñêðèïöèè. Ïðè ýòîì áûëî îòìå÷åíî, ÷òî ãåíû ÑÎÄ ïî-ðàçíîìó (ñïåöèôè÷íî) îòâå÷àþò •– íà óâåëè÷åíèå ïðîäóêöèè ÀÔÊ (O2 , 1O2, H2O2). Êîëè÷åñòâî òðàíñêðèïòîâ ïëàñòèäíîé èçîôîðìû ëèñòüåâ ïîäñîëíóõà, îáîçíà÷åííîé àâòîðàìè ÑÎÄha-1, óâåëè÷åíî â 2 ðàçà â îòâåò íà âíåêëåòî÷íóþ è õëîðîïëàñòíóþ ïðîäóêöèþ ñóïåðîêñèäíûõ àíèîí-ðàäèêàëîâ, òîãäà êàê äðóãèå ÀÔÊ íå âëèÿëè íà ýêñïðåññèþ äàííîãî ãåíà (Herbette et al., 2003). Êîëè÷åñòâî òðàíñêðèïòîâ äðóãîé èçîôîðìû (öèòîçîëüíîé ÑÎÄha-2) óâåëè÷åíî â îòâåò íà 1O2 è âíå•– êëåòî÷íóþ ïðîäóêöèþ O2 . Ïåðîêñèä âîäîðîäà ïðè ýòîì 469 íå îêàçûâàë âëèÿíèÿ íà òðàíñêðèïöèþ îáîèõ ãåíîâ (Herbette et al., 2003). Îäíàêî íà îñíîâàíèè èìåþùèõñÿ ëèòåðàòóðíûõ äàííûõ íåâîçìîæíî êîíêðåòíî îïðåäåëèòü ðîëü è ìåñòî ÀÔÊ â ïðîöåññàõ, ïðèâîäÿùèõ ê ýêñïðåññèè ãåíîâ ÑÎÄ. Äåéñòâèÿ ÀÔÊ, ïðè ýòîì, î÷åâèäíî, ìîãóò áûòü ïðÿìûìè, ïîñêîëüêó â ïðîìîòîðíûõ ó÷àñòêàõ ãåíîâ ÑÎÄ îáíàðóæåíû ëîêóñû, ÷óâñòâèòåëüíûå ê ÀÔÊ (Kardish et al., 1994; Tsukamoto et al., 2005), ÷òî áóäåò ðàññìîòðåíî íèæå. Òàêæå ó÷àñòèå ÀÔÊ â ýêñïðåññèè ãåíîâ ÑÎÄ ìîæåò áûòü îïîñðåäîâàíî, êàê îòìå÷åíî âûøå, èçìåíåíèåì îêèñëèòåëüíî-âîññòàíîâèòåëüíîãî ñîñòîÿíèÿ îïðåäåëåííûõ âíóòðèêëåòî÷íûõ ìîëåêóë, ÿâëÿþùèõñÿ çâåíüÿìè â öåïè ïåðåäà÷è ñèãíàëîâ.  ëþáîì ñëó÷àå ýêñïðåññèÿ ãåíîâ ÑÎÄ ÿâëÿåòñÿ ÷óâñòâèòåëüíîé ê ðåäîêñ-ñîñòîÿíèþ â êëåòêå (öèòîïëàçìàòè÷åñêîìó è(èëè) ÿäåðíîìó), è íàðóøåíèå áàëàíñà ìåæäó ïðîäóêöèåé è ëèêâèäàöèåé ÀÔÊ â ñòîðîíó ïîâûøåííîé ïðîäóêöèè, î÷åâèäíî, ÿâëÿåòñÿ íåîáõîäèìûì ñîáûòèåì â èçìåíåíèè ýêñïðåññèè ãåíîâ ÑÎÄ. Êðîìå ÀÔÊ â ðåãóëÿöèè àêòèâíîñòè ÑÎÄ ïðèíèìàþò ó÷àñòèå òàêæå èîíû êàëüöèÿ (Ca2+). Îòìå÷åíî, ÷òî óâåëè÷åíèå êîíöåíòðàöèè Ca2+ â öèòîçîëå êëåòîê ÿâëÿëîñü îäíèì èç íåîáõîäèìûõ óñëîâèé àêòèâàöèè ôåðìåíòà â ëèñòüÿõ êóêóðóçû (Jiang, Zhang, 2003). Îäíàêî â ðàáîòå Ïðàéñ è ñîàâòîðîâ (Price et al., 1994) ïîêàçàíî èíãèáèðóþùåå âëèÿíèå èîíîâ êàëüöèÿ íà àêòèâíîñòü ÑÎÄ â ðàñòåíèÿõ òàáàêà ïðè èõ îáðàáîòêå ðàñòâîðîì ïåðåêèñè âîäîðîäà. Îáðàáîòêà èíãèáèòîðîì êàëüöèåâûõ êàíàëîâ ëàíòàíîì ïðèâåëà ê óâåëè÷åíèþ àêòèâíîñòè ÑÎÄ. Ìåõàíèçì èíãèáèðîâàíèÿ äåéñòâèÿ ôåðìåíòà êàëüöèåì íåèçâåñòåí, íî, êàê ïðåäïîëàãàþò àâòîðû, âîçìîæíî, çäåñü äåéñòâóþò Ca-çàâèñèìûå ïðîòåèíêèíàçû è(èëè) ïðîòåàçû (Price et al., 1994). Îòìå÷åíî, ÷òî âíåøíÿÿ îáðàáîòêà ðàñòåíèé ðàéãðàñà ðàñòâîðîì êàëüöèÿ (CaCl2) íà àêòèâíîñòü ÑÎÄ íå âëèÿëà, õîòÿ è ïðèâîäèëà ê óâåëè÷åíèþ ñîäåðæàíèÿ âíóòðèêëåòî÷íîãî êàëüöèÿ (Jiang, Huang, 2001). Òàêèì îáðàçîì, èìåþùèåñÿ â ëèòåðàòóðå äàííûå îá ó÷àñòèè Ca2+ â ðåãóëÿöèè ÑÎÄ ðàçëè÷íû, è íåîáõîäèìû äàëüíåéøèå èññëåäîâàíèÿ â èçó÷åíèè äàííîãî âîïðîñà. ×òî êàñàåòñÿ ó÷àñòèÿ ôèòîãîðìîíîâ â ðåãóëÿöèè àêòèâíîñòè ÑÎÄ è ýêñïðåññèè åå ãåíîâ, òî çäåñü îòìå÷åíà íåêàÿ ñïåöèôèêà îòâåòîâ (Zhu, Scandalios, 1994; Herbette et al., 2003). Òàê, ïðè îáðàáîòêå ëèñòüåâ ïîäñîëíóõà æàñìîíîâîé êèñëîòîé, ýòåôîíîì, ñàëèöèëîâîé è àáñöèçîâîé êèñëîòàìè íå áûëî èçìåíåíèé â êîëè÷åñòâå ìÐÍÊ õëîðîïëàñòíîé èçîôîðìû ÑÎÄha-1 (Herbette et al., 2003). Îäíàêî ïðè îáðàáîòêå ðàñòåíèé ýòåôîíîì èìåëî ìåñòî íàêîïëåíèå òðàíñêðèïòîâ äðóãîé èçîôîðìû ÑÎÄ — öèòîçîëüíîé ÑÎÄha-2 (Herbette et al., 2003).  äðóãèõ ðàáîòàõ îòìå÷åíî âëèÿíèå àáñöèçîâîé êèñëîòû (Zhu, Scandalios, 1994; Kaminaka et al., 1999), ãèáåððåëëèíà è êèíåòèíà, íî íå ÀÁÊ (Kurepa etal., 1997) íà ðåãóëÿöèþ ãåíîâ ÑÎÄ. ×òî êàñàåòñÿ ÀÁÊ, îòìå÷åíî åå ó÷àñòèå â èíäóêöèè ýêñïðåññèè ãåíîâ, êîäèðóþùèõ ðàçíûå èçîôîðìû ôåðìåíòà: CuZnÑÎÄ (Sakamoto et al., 1995; Kaminaka et al., 1999), MnÑÎÄ (Bueno et al., 1998; Kaminaka et al., 1999) è FeÑÎÄ (Kaminaka et al., 1999). Ïðè ýòîì äåéñòâèå ôèòîãîðìîíîâ, êàê è â ñëó÷àå ÀÔÊ, ìîæåò áûòü ïðÿìûì, ïîñêîëüêó â ïðîìîòîðíûõ ó÷àñòêàõ ãåíîâ ÑÎÄ îáíàðóæåíû ëîêóñû, ÷óâñòâèòåëüíûå ê ôèòîãîðìîíàì (Scandalios, 1997; Bellaire et al., 2000). Êðîìå òîãî, î÷åâèäíî, ñóùåñòâóåò ñëîæíàÿ âíóòðèêëåòî÷íàÿ ðàáî÷àÿ ñåòü, âêëþ÷àþùàÿ â ñåáÿ êðîìå ôèòîãîðìîíîâ äðóãèå êîìïîíåíòû, â ÷àñòíîñòè óæå îòìå÷åííûå ÀÔÊ è èîíû êàëüöèÿ. Îòìå÷åíî îäíîâðåìåííîå ó÷àñòèå ÀÔÊ è Ca2+ â àêòèâàöèè 470 Â. Â. Áàðàíåíêî ÑÎÄ ïðè îáðàáîòêå ðàñòåíèé êóêóðóçû ðàñòâîðàìè ÀÁÊ (Jiang, Zhang, 2003). Ê ñîæàëåíèþ, àâòîðû íå èçó÷àëè êîíöåíòðàöèþ ÀÁÊ â êëåòêàõ, à ïðèìåíèëè òîëüêî ýêçîãåííóþ îáðàáîòêó ðàñòåíèé ðàñòâîðàìè ÀÁÊ. Ïðè ýòîì •– îòìå÷åíî óâåëè÷åíèå ïðîäóêöèè O2 , èîíîâ êàëüöèÿ è àêòèâàöèè ÑÎÄ. Îáðàáîòêà ðàñòåíèé èíãèáèòîðàìè ÍÀÄÔîêñèäàçû èìèäàçîëîì è ïèðèäèíîì áëîêèðîâàëà óâåëè•– ÷åíèå ïðîäóêöèè O2 ; àêòèâíîñòü ÑÎÄ ïðè ýòîì íå èçìåíÿëàñü (Jiang, Zhang, 2003). Òàêèì îáðàçîì, äëÿ àêòèâàöèè ÑÎÄ íåîáõîäèìî óâåëè÷åíèå êîëè÷åñòâà ñóïåðîêñèäíûõ ðàäèêàëîâ. Ïðè îáðàáîòêå ðàñòåíèé õåëàòîðîì êàëüöèÿ (ÝÃÒÀ) è èíãèáèòîðàìè êàëüöèåâûõ êàíàëîâ (âåðàïàìèëîì è La3+) íå îòìå÷åíî àêòèâàöèè ÍÀÄÔ-îêñèäàçû, óâåëè÷åíèÿ êîëè÷åñòâà ÀÔÊ è àêòèâíîñòè ÑÎÄ. Òàêèì îáðàçîì, íå òîëüêî ÀÔÊ, íî è Ca2+ âîâëå÷åíû â àêòèâàöèþ ÑÎÄ, âûçâàííóþ îáðàáîòêîé ÀÁÊ. Ïðè ýòîì ìû âñå æå ìîæåì óñòàíîâèòü íåêóþ ïîñëåäîâàòåëüíîñòü ñîáûòèé: óâåëè÷åíèå êîíöåíòðàöèè Ca2+ â êëåòêå íåîáõîäèìî äëÿ àêòèâàöèè ÍÀÄÔ-îêñèäàçû è ñîîòâåòñòâåííî âîçðàñòàíèÿ ïðîäóêöèè ñóïåðîêñèäíûõ ðàäèêàëîâ. Îäíàêî íå âñåãäà èçìåíåíèÿ êîíöåíòðàöèè Ca2+ â êëåòêå ïðåäøåñòâóþò óâåëè÷åíèþ ïðîäóêöèè ÀÔÊ. Îòìå÷åíî, ÷òî â êëåòêàõ ñóñïåíçèéíîé êóëüòóðû òàáàêà, îáðàáîòàííûõ ðàñòâîðîì •– ñàëèöèëîâîé êèñëîòû, âîçðàñòàíèå ïðîäóêöèè O2 ïðîèñõîäèò ðàíüøå óâåëè÷åíèÿ êîíöåíòðàöèè Ca2+ â êëåòêå (Kawano et al., 1998).  ëþáîì ñëó÷àå ýòè ñîáûòèÿ òåñíî ñâÿçàíû è íåîáõîäèìû äëÿ àêòèâàöèè ÑÎÄ. Ðåãóëèðóþùåå âëèÿíèå íà àêòèâíîñòü ÑÎÄ îêàçûâàåò òàêæå ãëóòàòèîí. Îòìå÷åíî ó÷àñòèå ãëóòàòèîíà â ýêñïðåññèè ãåíà, êîäèðóþùåãî öèòîçîëüíóþ èçîôîðìó CuZnÑÎÄ â êëåòêàõ ëèñòüåâ òàáàêà (Herouart et al., 1993). Ïðè ýòîì ïîêàçàíî, ÷òî òîëüêî âîññòàíîâëåííûé ãëóòàòèîí (íî íå åãî îêèñëåííàÿ ôîðìà) èíäóöèðóåò ýêñïðåññèþ ãåíà. Òàêèì îáðàçîì, îêèñëåíèå ãëóòàòèîíà èëè åãî âîññòàíîâëåíèå (ò. å. óæå îòìå÷åííîå ðåäîêñ-ñîñòîÿíèå) âëèÿåò íà ýêñïðåññèþ ãåíîâ ÑÎÄ. Ìåõàíèçì äåéñòâèÿ ãëóòàòèîíà ïðè ýòîì íå óñòàíîâëåí.  ýêñïåðèìåíòàõ íà êëåòêàõ ïå÷åíè êðûñ ïîêàçàíî, ÷òî ââåäåíèå ãëóòàòèîíà, öèñòåèíà è äðóãèõ ñóëüôãèäðèëüíûõ ñîåäèíåíèé ïðèâåëî ê àêòèâàöèè ÑÎÄ, ÷òî, ïî ìíåíèþ àâòîðîâ, îáóñëîâëåíî âîññòàíîâëåíèåì SH-ñîåäèíåíèÿìè èîíîâ ìåäè (Cu2+) â àêòèâíîì öåíòðå ôåðìåíòà (Hoshino et al., 1985). Âàæíîé ñèãíàëüíîé ìîëåêóëîé â êëåòêàõ ðàñòåíèé ÿâëÿåòñÿ îêñèä àçîòà (NO) (Neill et al., 2003). Îòìå÷åíî ó÷àñòèå NO â ðåãóëÿöèè ýêñïðåññèè ãåíîâ ÑÎÄ (Herbette et al., 2003). Ïðè ýòîì ïîêàçàíî, ÷òî êîëè÷åñòâî ìÐÍÊ ãåíà, êîäèðóþùåãî ÑÎÄha-1, íå èçìåíèëîñü â îòâåò íè íà ïðîäóêöèþ NO, íè íà åãî óäàëåíèå, òîãäà êàê êîëè÷åñòâî òðàíñêðèïòîâ äðóãîé èçîôîðìû (ÑÎÄha-2) çíà÷èòåëüíî óâåëè÷èëîñü ïðè îáåèõ îáðàáîòêàõ (Herbette et al., 2003). Òàêèì îáðàçîì, êàê è â ñëó÷àå ÀÔÊ, ìû âèäèì ñïåöèôèêó îòâåòîâ ãåíîâ ÑÎÄ íà èçìåíåíèå êîíöåíòðàöèè NO. Îäíàêî íåïîñðåäñòâåííàÿ ðîëü NO â ýêñïðåññèè ãåíîâ ÑÎÄ íå óñòàíîâëåíà. Îòìå÷åíî òàêæå ó÷àñòèå ôîñôàòàç è(èëè) êèíàç è ñîîòâåòñòâåííî ïðîöåññîâ ôîñôîðèëèðîâàíèÿ—äåôîñôîðèëèðîâàíèÿ â ðåãóëÿöèè ýêñïðåññèè ãåíîâ ÑÎÄ (Herbette et al., 2003). Îáðàáîòêà ëèñòüåâ ïîäñîëíóõà èíãèáèòîðîì ôîñôàòàçû êàíòàðèäèíîì, à òàêæå èíãèáèòîðîì ñåðèí/òðåîíèí-êèíàçû ñòàóðîñïîðèíîì íå âëèÿëà íà ýêñïðåññèþ ãåíà ÑÎÄha-1, òîãäà êàê êîëè÷åñòâî òðàíñêðèïòîâ ãåíà, êîäèðóþùåãî ÑÎÄha-2, óâåëè÷èëîñü ïðè îáåèõ îáðàáîòêàõ (Herbette et al., 2003). Î÷åâèäíî, ôîñôîðèëèðîâàíèå—äåôîñôîðèëèðîâàíèå îïðåäåëåííûõ áåëêîâ ïðèâîäèò ê èçìåíåíèþ èõ àêòèâíîñòè, ÷òî â ñâîþ î÷åðåäü êîñâåííî âëèÿåò íà ýêñïðåññèþ ãåíîâ ÑÎÄ. Âûñêàçàíî ïðåäïîëîæåíèå î òîì, ÷òî ïðîöåññû ôîñôîðèëèðîâàíèÿ—äåôîñôîðèëèðîâàíèÿ ïðè ýòîì ìîäóëèðóþòñÿ èçìåíåíèåì êîíöåíòðàöèè ÀÔÊ â êëåòêå (Herbette et al., 2003). Òàêèì îáðàçîì, ðàññìîòðåíî âîçìîæíîå ó÷àñòèå ÀÔÊ, èîíîâ êàëüöèÿ, ãëóòàòèîíà, ôèòîãîðìîíîâ, êèíàç è(èëè) ôîñôàòàç â àêòèâàöèè ÑÎÄ è ýêñïðåññèè åå ãåíîâ. Î÷åâèäíî, ýòî äàëåêî íå ïîëíûé ïåðå÷åíü, è åùå ïðåäñòîèò îïðåäåëèòü è èçó÷èòü íîâûå êîìïîíåíòû è èõ ìåñòî è ðîëü â ðåãóëÿöèè ÑÎÄ. à å í û Ñ Î Ä: ñ ï å ö è ô è ê à è õ î ò â å ò î â. Äëÿ ïîíèìàíèÿ ìåõàíèçìîâ, ïðè ïîìîùè êîòîðûõ ãåíîì âîñïðèíèìàåò âîçäåéñòâèÿ ñòðåññîâûõ ôàêòîðîâ, íåîáõîäèìî èäåíòèôèöèðîâàòü ñîîòâåòñòâóþùèå ãåíû, èçó÷èòü èõ ñòðóêòóðó è ðåãóëÿöèþ. Âûäåëåíû è èçó÷åíû ãåíû, êîäèðóþùèå ðàçëè÷íûå èçîôîðìû ÑÎÄ â êëåòêàõ êóêóðóçû (Scandalios, 1997), òàáàêà (Van Camp et al., 1996b), ðèñà (Kaminaka et al., 1999; Lee et al., 2001), àðàáèäîïñèñà (Kleibenstein et al., 1998) è äð.  ÷àñòíîñòè, â ëèñòüÿõ êóêóðóçû èçîôîðìû ÑÎÄ êîäèðóþòñÿ 9 íåàëëåëüíûìè ãåíàìè: 4 ãåíàìè öèòîçîëüíîé ôîðìû CuZnÑÎÄ (Sod-2, Sod-4, Sod-4A è Sod-5), 4 — ìèòîõîíäðèàëüíîé MnÑÎÄ (Sod-3.1, Sod-3.2, Sod-3.3 è Sod-3.4) è 1 ãåíîì õëîðîïëàñòíîé CuZnÑÎÄ (Zhu, Scandalios, 1994; Scandalios, 1997). Èçó÷åíèå àìèíîêèñëîòíûõ ïîñëåäîâàòåëüíîñòåé èçîôîðì ÑÎÄ êàæäîãî ñåìåéñòâà ïîêàçàëî èõ ãîìîëîãè÷íîñòü â ïðåäåëàõ ñåìåéñòâ (95 %); êîäèðóþùèå ó÷àñòêè ñîîòâåòñòâóþùèõ ãåíîâ òàêæå âûñîêîãîìîëîãè÷íû (Kernodle, Scandalios, 1996; Scandalios, 1997). Îäíàêî ýòè ãåíû, êàê ìû îòìåòèëè âûøå, ïî-ðàçíîìó îòâå÷àþò íà âîçäåéñòâèÿ ñòðåññîâûõ ôàêòîðîâ, óâåëè÷åíèå êîëè÷åñòâà ÀÔÊ, îáðàáîòêó ôèòîãîðìîíàìè è ò. ä. Îíè ïî-ðàçíîìó ðåãóëèðóþòñÿ âî âðåìÿ ðîñòà è ðàçâèòèÿ ðàñòåíèé (Zhu, Scandalios, 1994; Guan, Scandalios, 1998). Òàê, êîëè÷åñòâî ìàòðè÷íîé ÐÍÊ CuZnÑÎÄ õëîðîïëàñòîâ ìîëîäûõ ëèñòüåâ òàáàêà áûëî â 4 ðàçà âûøå ïî ñðàâíåíèþ ñ òàêîâûì çðåëûõ ëèñòüåâ (Kurepa et al., 1997). ×òî êàñàåòñÿ FeÑÎÄ, òî åå àêòèâíîñòü, íàîáîðîò, ïîâûøàëàñü ñ óâåëè÷åíèåì âîçðàñòà ðàñòåíèé. Ïîêàçàíî, ÷òî êîëè÷åñòâî òðàíñêðèïòîâ ãåíîâ Sod-4 è Sod-4A áûëî îäèíàêîâûì ïðè ïðîðàùèâàíèè ñåìÿí êóêóðóçû (Guan, Scandalios, 1998), îäíàêî â êëåòêàõ ìîëîäûõ ëèñòüåâ ïðîðîñòêîâ çíà÷èòåëüíî ïðåîáëàäàëî êîëè÷åñòâî òðàíñêðèïòîâ ãåíà Sod-4A (Guan, Scandalios, 1998). Êðîìå òîãî, ãåíû ïî-ðàçíîìó îòâå÷àëè íà ðàçíîîáðàçíûå ñòðåññîâûå âîçäåéñòâèÿ, òàêèå êàê èíòåíñèâíîå îñâåùåíèå, îáðàáîòêà öåðêîñïîðèíîì, H2O2 è ÀÁÊ (Kernodle, Scandalios, 1996; Guan, Scandalios, 1998). Ïðè÷èíîé ðàçëè÷íîé ðåãóëÿöèè ýêñïðåññèè ãåíîâ ÑÎÄ â ïðîöåññå ðîñòà è ðàçâèòèÿ, à òàêæå ïðè ñòðåññîâûõ âîçäåéñòâèÿõ ÿâëÿåòñÿ ðàçëè÷èå èõ ïðîìîòîðíûõ ó÷àñòêîâ, è ýòî ãîâîðèò î òîì, ÷òî îíè ðåãóëèðóþòñÿ ðàçíûìè ìåõàíèçìàìè. Òàê, ïðîìîòîðíûå ó÷àñòêè ãåíà, êîäèðóþùåãî ïëàñòèäíóþ CuZnÑÎÄ, ñîäåðæàò ëîêóñû, êîíòðîëèðóåìûå ñâåòîâûìè ñèãíàëàìè, ÷òî, î÷åâèäíî, ãîâîðèò îá ó÷àñòèè â ýòèõ ïðîöåññàõ êèñëîðîäíûõ ðàäèêàëîâ (Kardish et al., 1994). Êðîìå òîãî, â äàííûõ ãåíàõ îáíàðóæåíû ó÷àñòêè, êîòîðûå äåéñòâóþò íå â óñëîâèÿõ îêèñëèòåëüíîãî ñòðåññà, à â ïðîöåññàõ ðîñòà è ðàçâèòèÿ ðàñòåíèé. Ïðîìîòîðíûé ó÷àñòîê ãåíà Sod-3.1 â ëèñòüÿõ êóêóðóçû ñîäåðæèò ëîêóñ, îòâå÷àþùèé íà âîçäåéñòâèå ñàëèöèëîâîé êèñëîòû, òîãäà êàê â äðóãèõ ãåíàõ ýòîãî ñåìåéñòâà (Sod-3.2, Sod-3.3 è Sod-3.4) äàííûé ëîêóñ îòñóòñòâóåò (Scandalios, 1997). Îäíàêî ïîñëåäíèå èìåþò ó÷àñòêè, îòâå÷àþùèå íà âîçäåéñòâèå Ñóïåðîêñèääèñìóòàçà â êëåòêàõ ðàñòåíèé ÀÁÊ, òîãäà êàê ãåí Sod-3.1 íå èìååò òàêîâîãî (Scandalios, 1997).  ïðîìîòîðíîì ó÷àñòêå ãåíà, êîäèðóþùåãî öèòîçîëüíóþ CuZnÑÎÄ â ïðîðîñòêàõ ðèñà, îáíàðóæåí cis-ýëåìåíò, ÷óâñòâèòåëüíûé ê îêèñëèòåëüíîìó ñòðåññó è íàçâàííûé CORE (coordinative regulatory element for antioxidative defense; Tsukamoto et al., 2005). Ýòîò ýëåìåíò îòâå÷àë íà îáðàáîòêó ìåòèëâèîëîãåíîì (èíäóêòîðîì ñóïåðîêñèäíûõ ðàäèêàëîâ) è íå àêòèâèðîâàëñÿ ïðè äåéñòâèè H2O2. Òàêæå îòìå÷åíî ó÷àñòèå MAP-êèíàç â èçìåíåíèè àêòèâíîñòè CORE è ýêñïðåññèè ãåíà (Tsukamoto et al., 2005). Ïðè ýòîì MAP-êèíàçû âûñòóïàþò â ðîëè íåãàòèâíîãî ðåãóëÿòîðà ýòèõ ïðîöåññîâ: îáðàáîòêà îáðàçöîâ èíãèáèòîðîì MAP-êèíàç ñòàóðîñïîðèíîì óâåëè÷èâàëà êàê àêòèâíîñòü CORE, òàê è ýêñïðåññèþ ãåíà, êîäèðóþùåãî CuZnÑÎÄ (Tsukamoto et al., 2005). Òàêèì îáðàçîì, ýêñïðåññèÿ ãåíîâ ÑÎÄ êîíòðîëèðóåòñÿ óíèêàëüíûìè äëÿ êàæäîãî ãåíà ìåõàíèçìàìè, ÷òî îáóñëîâëåíî ðàçëè÷èåì èõ ïðîìîòîðíûõ ó÷àñòêîâ. Ó Escherichia coli çà ýêñïðåññèþ ãåíà ÑÎÄ îòâå÷àåò äâóõãåííûé ëîêóñ soxRS, â êîòîðîì îáà ãåíà äåéñòâóþò ïîñëåäîâàòåëüíî (Hidalgo, Demple, 1997). Ïðîäóêò ïåðâîãî ãåíà soxR (SoxR) ÿâëÿåòñÿ ðåäîêñ-÷óâñòâèòåëüíûì; åãî ïðÿìîå îêèñëåíèå èëè âîññòàíîâëåíèå àíèîí-ðàäèêàëàìè ñóïåðîêñèäà ïðèâîäèò ê àêòèâàöèè èëè èíãèáèðîâàíèþ òðàíñêðèïöèè ñëåäóþùåãî ãåíà — soxS, êîòîðûé îòâå÷àåò çà ñèíòåç àêòèâàòîðà òðàíñêðèïöèè (SoxS), íåïîñðåäñòâåííî ñòèìóëèðóþùåãî ýêñïðåññèþ ãåíà ÑÎÄ (Hidalgo, Demple, 1997).  êëåòêàõ ðàñòåíèé íå îáíàðóæåíî ãîìîëîãîâ òðàíñêðèïöèîííûõ ôàêòîðîâ SoxR è SoxS, îäíàêî èçâåñòíû äðóãèå ôàêòîðû òðàíñêðèïöèè, òàêèå êàê AP-1 (activator protein-1) è NF-IB (nuclear factor) (Scandalios, 1997). Âîçìîæíî, èçìåíåíèå ðåäîêñ-ñîñòîÿíèÿ ôàêòîðîâ òðàíñêðèïöèè âëèÿåò íà ýêñïðåññèþ ãåíîâ Sod (Zhu, Scandalios, 1994). Ð å ã ó ë ÿ ö è ÿ à ê ò è â í î ñ ò è è ç î ô î ð ì Ñ Î Ä, íàõîäÿùèõñÿ â ðàçëè÷íûõ âíóòðèêëåòî÷íûõ ê î ì ï à ð ò ì å í ò à õ. Òàêæå ïðåäñòàâëÿåò èíòåðåñ ñïåöèôè÷åñêàÿ ðåãóëÿöèÿ èçîôîðì ÑÎÄ, ò. å. òî, êàêèì îáðàçîì ìèòîõîíäðèàëüíàÿ MnÑÎÄ îòâå÷àåò íà ñîáûòèÿ â ìèòîõîíäðèÿõ, à õëîðîïëàñòíàÿ FeÑÎÄ — â õëîðîïëàñòàõ, òîãäà êàê âñå ãåíû ÑÎÄ ðàñïîëîæåíû â ÿäðå. Î÷åâèäíî, ñóùåñòâóþò ñèãíàëüíûå êîìïîíåíòû, ñïåöèôè÷íûå äëÿ êàæäîãî êëåòî÷íîãî êîìïàðòìåíòà. Ýòè ìîëåêóëû, âåðîÿòíî, ÿâëÿþòñÿ ïåðâè÷íûìè ñåíñîðàìè è îäíîâðåìåííî ïåðåíîñ÷èêàìè; îíè äîëæíû áûòü íåáîëüøèìè ïî ìîëåêóëÿðíîé ìàññå, ïîñêîëüêó èì íåîáõîäèìî áûñòðî òðàíñïîðòèðîâàòüñÿ èç êîìïàðòìåíòà â ÿäðî. Ïðåäïîëàãàþò, ÷òî òàêîâûìè ÿâëÿþòñÿ îêñèëèïèíû, ïðîèçâîäíûå îêèñëåíèÿ ñâîáîäíûõ æèðíûõ êèñëîò (Bowler, 1992). Æèðíûå êèñëîòû, ñïåöèôè÷åñêèå äëÿ õëîðîïëàñòîâ, ìèòîõîíäðèé è ïëàçìàòè÷åñêîé ìåìáðàíû, îêèñëÿþòñÿ àêòèâíûìè ôîðìàìè êèñëîðîäà ñ îáðàçîâàíèåì ãèäðîôèëüíûõ ìîëåêóë, êîòîðûå ìîãóò òðàíñïîðòèðîâàòüñÿ â ÿäðî è âçàèìîäåéñòâîâàòü ñ îïðåäåëåííûìè ôàêòîðàìè òðàíñêðèïöèè, ÷òî ïðèâîäèò ê àêòèâàöèè ýêñïðåññèè ãåíà, êîäèðóåìîãî íåîáõîäèìóþ ôîðìó ÑÎÄ. Àíàëîãàìè îêñèëèïèíîâ â êëåòêàõ æèâîòíûõ è ÷åëîâåêà ÿâëÿþòñÿ ïðîñòàãëàíäèíû, ëåéêîòðèåíû è ëèïîêñèíû (Samuelsson et al., 1987). Ìû ðàññìîòðåëè ó÷àñòèå â ðåãóëÿöèè àêòèâíîñòè ÑÎÄ è ýêñïðåññèè åå ãåíîâ ðàçëè÷íûõ âíóòðèêëåòî÷íûõ ìàêðîìîëåêóë. Ñêîðåå âñåãî, îíè ðàáîòàþò íå ñàìîñòîÿòåëüíî, à âîâëå÷åíû â ñëîæíóþ âíóòðèêëåòî÷íóþ ðàáî÷óþ ñåòü. Îäíàêî ìíîãèå äåòàëè ôóíêöèîíèðîâàíèÿ ðàáî÷åé ñåòè íå óñòàíîâëåíû. 471 Òàêèì îáðàçîì, ñóïåðîêñèääèñìóòàçà èãðàåò âàæíóþ ðîëü â çàùèòå êëåòîê è òêàíåé îò îêèñëèòåëüíûõ ïîâðåæäåíèé â óñëîâèÿõ ðîñòà è ðàçâèòèÿ ðàñòåíèé, à òàêæå ïðè äåéñòâèè íåáëàãîïðèÿòíûõ ôàêòîðîâ. Îäíàêî ïðè ðàáîòå ÑÎÄ îáðàçóåòñÿ ïåðîêñèä âîäîðîäà, êîòîðûé, êàê óæå îòìå÷åíî, ÿâëÿåòñÿ èíãèáèòîðîì ôåðìåíòà. Ïîýòîìó ýôôåêòèâíîå ôóíêöèîíèðîâàíèå ÑÎÄ â çíà÷èòåëüíîé ñòåïåíè îïðåäåëÿåòñÿ ôóíêöèîíèðîâàíèåì äðóãèõ êîìïîíåíòîâ ñèñòåìû çàùèòû, â ÷àñòíîñòè òåõ, êîòîðûå óäàëÿþò ïåðîêñèä âîäîðîäà (êàòàëàç, ïåðîêñèäàç) è ôåðìåíòîâ àñêîðáàò-ãëþòàòèîííîãî öèêëà. Ñïèñîê ëèòåðàòóðû Ãðèøêî Â. Í., Ñûùèêîâ Ä. 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Baranenko Institute of Botany, National Academy of Sciences of the Ukraine, Kiev; e-mail: [email protected] Superoxide dismutase (SOD) is one of the key components of defense system, which protect cells and tissues from oxidative destruction. The unique nature of this enzyme among other antioxidants, its localization in different intracellular compartment are reviewed in addition to enzyme behaviour under unflavourable influences. Besides, we considered questions of regulation of SOD activity, participation of such intracellular macromolecules as reactive oxygen species, calcium iones, phytogormones, and nitric oxide in this regulation, as well as phosphoralation/dephosphorylation process.
