The gamma subunit of the Escherichia coli ATP synthase. Mutations in the carboxyl-terminal region restore energy coupling to the amino-terminal mutant gamma Met-23-->Lys.
The gamma subunit of the Escherichia coli ATP synthase. Mutations in the carboxyl-terminal region restore energy coupling to the amino-terminal mutant gamma Met-23-->Lys.
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大肠杆菌 ATP 合酶的 γ 亚基。
DOI：
10.1016/s0021-9258(18)54014-x
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
M. Futai
中科院分区：
文献类型：
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作者：
R. Nakamoto;M. Maeda;M. Futai
先前报道大肠杆菌ATP合酶中的γ亚基突变γ Met-23->Lys或Arg导致ATP酶催化和H+易位之间显著低效的能量偶联（Shin，K.，Nakamoto，R.K.，Maeda，M.，和Futai，M.（1992）J.Biol.Chem.267，20835-20839）。在本文中，我们报告了γ亚基中的第二位点突变可以抑制γ Met-23->Lys的作用。通过筛选随机诱变的uncG（γ Met-23->Lys），在羧基端区域鉴定出8个突变;携带γ Arg-242->Cys、γ Gln-269->Arg、γ Ala-270->瓦尔、γ Ile-272->Thr、γ Thr-273->Ser、γ Glu-278->Gly、γ Ile-279->Thr的菌株，或γ瓦尔-280->Ala与γ Met-23->Lys的组合能够通过氧化磷酸化生长。双突变菌株制备的膜中的H+泵测定表明，有效的ATP依赖的H+运输恢复。有趣的是，单突变γ Gln-269->Arg或γ Thr-273->Ser通过氧化磷酸化引起生长减少;然而，当这些突变与γ Met-23->Lys组合时，生长显著增加。此外，携带γ Met-23->Lys、γ Gln-269->Arg或γ Thr-273->Ser作为单突变的菌株是温度敏感的，而具有γ Met-23->Lys/γ Gln-269->Arg或γ Met-23->Lys/γ Thr-273->Ser双突变的菌株是热稳定的。综上所述，这些结果强烈表明γ Met-23、γ Arg-242和γ Gln-269至γ瓦尔-280之间的区域彼此接近并相互作用以介导有效的能量偶联。
The gamma subunit mutations, gamma Met-23–>Lys or Arg, in the Escherichia coli ATP synthase were previously reported to cause dramatically inefficient energy coupling between ATPase catalysis and H+ translocation (Shin, K., Nakamoto, R.K., Maeda, M., and Futai, M. (1992) J. Biol. Chem. 267, 20835-20839). In this paper, we report that second-site mutations in the gamma subunit can suppress the effects of gamma Met-23–>Lys. By screening randomly mutagenized uncG (gamma Met-23–>Lys), eight mutations in the carboxyl-terminal region were identified; strains carrying gamma Arg-242–>Cys, gamma Gln-269–>Arg, gamma Ala-270–>Val, gamma Ile-272–>Thr, gamma Thr-273–>Ser, gamma Glu-278–>Gly, gamma Ile-279–>Thr, or gamma Val-280–>Ala in combination with gamma Met-23–>Lys were able to grow by oxidative phosphorylation. H+ pumping assayed in membranes prepared from double mutation strains demonstrated that efficient ATP-dependent H+ transport was restored. Interestingly, the single mutations, gamma Gln-269–>Arg or gamma Thr-273–>Ser, caused reduced growth by oxidative phosphorylation; however, when these mutations were in combination with gamma Met-23–>Lys, growth was substantially increased. Furthermore, strains carrying gamma Met-23–>Lys, gamma Gln-269–>Arg, or gamma Thr-273–>Ser as single mutations were temperature sensitive, whereas, strains with the double mutations, gamma Met-23–>Lys/gamma Gln-269–>Arg or gamma Met-23–>Lys/gamma Thr-273–>Ser, were thermally stable. Taken together, these results strongly suggest that gamma Met-23, gamma Arg-242, and the region between gamma Gln-269 to gamma Val-280 are close to each other and interact to mediate efficient energy coupling.