生物
分泌物
ATP结合盒运输机
膜转运蛋白
转运蛋白
细菌外膜
生物化学
孔蛋白
内膜
大肠杆菌
膜蛋白
细胞生物学
整体膜蛋白
运输机
膜
基因
作者
Hong‐Wu Zhao,James Lee,Jue Chen
出处
期刊:Cell
[Elsevier]
日期:2022-09-01
卷期号:185 (18): 3329-3340.e13
被引量:7
标识
DOI:10.1016/j.cell.2022.07.017
摘要
Type 1 secretion systems (T1SSs) are widespread in pathogenic Gram-negative bacteria, extruding protein substrates following synthesis of the entire polypeptide. The Escherichia coli hemolysin A secretion system has long been considered a prototype in structural and mechanistic studies of T1SSs. Three membrane proteins-an inner membrane ABC transporter HlyB, an adaptor protein HlyD, and an outer membrane porin TolC-are required for secretion. However, the stoichiometry and structure of the complex are unknown. Here, cryo-electron microscopy (cryo-EM) structures determined in two conformations reveal that the inner membrane complex is a hetero-dodecameric assembly comprising three HlyB homodimers and six HlyD subunits. Functional studies indicate that oligomerization of HlyB and HlyD is essential for protein secretion and that polypeptides translocate through a canonical ABC transporter pathway in HlyB. Our data suggest that T1SSs entail three ABC transporters, one that functions as a protein channel and two that allosterically power the translocation process.
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