大肠杆菌ATP合酶F0F1复合物的稳定性取决于γ亚基的谷氨酰胺-269与β亚基环上的天冬氨酸-301-天冬氨酸-305之间的相互作用。

Stability of the Escherichia coli ATP synthase F0F1 complex is dependent on interactions between gamma Gln-269 and the beta subunit loop beta Asp-301-beta Asp-305.

作者信息

Omote H, Tainaka K, Fujie K, Iwamoto-Kihara A, Wada Y, Futai M

机构信息

Institute of Scientific and Industrial Research, Osaka University, Osaka, Ibaraki, 567-0047, Japan.

出版信息

Arch Biochem Biophys. 1998 Oct 15;358(2):277-82. doi: 10.1006/abbi.1998.0856.

DOI:10.1006/abbi.1998.0856

PMID:9784240

Abstract

The role of the conserved sequence motif 301DDLTDP306 in the F0F1 ATP synthase beta subunit was assessed by mutagenic analysis in the Escherichia coli enzyme. Mutations gave variable effects on F1 sector activity, stability, and membrane binding to the F0 sector. Upon solubilization, F1 sectors of the betaD302E and betaD305E mutants (betaAsp-302 and betaAsp-305 replaced by glutamate) dissociated into subunits, while mutants with other beta305 substitutions failed to assemble. Membrane ATPase activities of beta301 and 302 mutants were 20-70% of wild type. Replacements of the gamma subunit Gln-269 had similar effects. The membrane ATPase activities of the gammaQ269E or gammaQ269D mutants were significantly lower and their F1 sectors dissociated into subunits upon solubilization. These results suggest that the beta301-305 loop and the gamma subunit region around Gln-269 form a key region for the assembly of alpha3 beta3 gamma complex. These results are consistent with the X-ray crystallographic structure of bovine F1 (J. P. Abrahams, A. G. W. Leslie, R. Lutter, and J. E. Walker (1994) Nature 370, 621-628) where the beta301DDLTD305 loop directly interacts with gammaGln-269.

摘要

通过对大肠杆菌中的酶进行诱变分析，评估了保守序列基序301DDLTDP306在F0F1 ATP合酶β亚基中的作用。突变对F1区段活性、稳定性以及与F0区段的膜结合产生了不同影响。溶解后，βD302E和βD305E突变体（β天冬氨酸-302和β天冬氨酸-305被谷氨酸取代）的F1区段解离成亚基，而其他β305取代的突变体无法组装。β301和302突变体的膜ATP酶活性为野生型的20%-70%。γ亚基Gln-269的替换产生了类似的效果。γQ269E或γQ269D突变体的膜ATP酶活性显著降低，并且它们的F1区段在溶解后解离成亚基。这些结果表明，β301-305环和Gln-269周围的γ亚基区域形成了α3β3γ复合体组装的关键区域。这些结果与牛F1的X射线晶体结构（J. P. Abrahams、A. G. W. Leslie、R. Lutter和J. E. Walker（1994年）《自然》370，621-628）一致，其中β301DDLTD305环直接与γGln-269相互作用。