FUMARASE-C, THE STABLE FUMARASE OF ESCHERICHIA-COLI, IS CONTROLLED BY THE SOXRS REGULON
FUMARASE-C, THE STABLE FUMARASE OF ESCHERICHIA-COLI, IS CONTROLLED BY THE SOXRS REGULON
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DOI：
10.1073/pnas.89.13.5892
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发表时间：
1992-07-01
影响因子：
11.1
通讯作者：
FRIDOVICH, I
中科院分区：
文献类型：
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作者：
LIOCHEV, SI;FRIDOVICH, I
延胡索酸酶C强烈诱导百草枯在大肠杆菌的亲本菌株，但没有诱导缺乏soxRS反应的菌株。此外，组成型表达soxRS调节子的菌株比亲本菌株含有更多的辅酶C。含锰超氧化物歧化酶和葡萄糖-6-磷酸脱氢酶，soxRS调节子的成员，同样诱导百草枯。葡萄糖-6-磷酸脱氢酶的突变缺陷增加了百草枯对脱氢酶C的诱导。对于含锰的超氧化物歧化酶，百草枯的反应也增强了葡萄糖-6-磷酸脱氢酶缺陷株。在tac-sodA融合菌株中，异丙基-β-D-硫代半乳糖苷引起含锰超氧化物歧化酶的过量产生，并没有减少百草枯对富马酸酶C或葡萄糖-6-磷酸脱氢酶的诱导，并且这些酶的诱导对百草枯更敏感当细胞在琥珀酸盐而不是LB培养基上生长时。这些结果表明，脱氢酶C是soxRS调节子的一员，该调节子不响应O2（-）浓度的变化，但可能确实响应NADPH与NADP+比值降低的某些结果。
Fumarase C was strongly induced by paraquat in a parental strain of Escherichia coli but was not induced in a strain lacking the soxRS response. Moreover, a strain that constitutively expresses the soxRS regulon contained more fumarase C than did the parental strain. The Mn-containing superoxide dismutase and glucose-6-phosphate dehydrogenase, members of the soxRS regulon, were similarly induced by paraquat. Mutational defects in glucose-6-phosphate dehydrogenase increased the induction of fumarase C by paraquat. For Mn-containing superoxide dismutase, responsiveness to paraquat was also enhanced in the glucose-6-phosphate dehydrogenase-defective strains. Overproduction of the Mn-containing superoxide dismutase, elicited by isopropyl-beta-D-thiogalactoside in a tac-sodA fusion strain, did not diminish induction of fumarase C or of glucose-6-phosphate dehydrogenase by paraquat, and induction of these enzymes was more sensitive to paraquat when the cells were growing on succinate rather than on LB medium. These results indicate that fumarase C is a member of the soxRS regulon and that this regulon does not respond to changes in O2(-) concentration but perhaps does respond to some consequence of a decrease in the ratio of NADPH to NADP+.