The C-terminal tail of the bacterial translocation ATPase SecA modulates its activity

eLife

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[1] Center for Molecular Biology of Heidelberg University (ZMBH), German Cancer Research Center (DKFZ), ZMBH-DKFZ Alliance, Heidelberg, Germany;Institute for Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham, United Kingdom;Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom;Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom;

关键词: SecA;    ribosome;    protein translocation;    protein secretion;    metal-binding domain;    SAXS;    E. coli;   

DOI  :  10.7554/eLife.48385

来源: publisher

【 摘 要 】

10.7554/eLife.48385.001In bacteria, the translocation of proteins across the cytoplasmic membrane by the Sec machinery requires the ATPase SecA. SecA binds ribosomes and recognises nascent substrate proteins, but the molecular mechanism of nascent substrate recognition is unknown. We investigated the role of the C-terminal tail (CTT) of SecA in nascent polypeptide recognition. The CTT consists of a flexible linker (FLD) and a small metal-binding domain (MBD). Phylogenetic analysis and ribosome binding experiments indicated that the MBD interacts with 70S ribosomes. Disruption of the MBD only or the entire CTT had opposing effects on ribosome binding, substrate-protein binding, ATPase activity and in vivo function, suggesting that the CTT influences the conformation of SecA. Site-specific crosslinking indicated that F399 in SecA contacts ribosomal protein uL29, and binding to nascent chains disrupts this interaction. Structural studies provided insight into the CTT-mediated conformational changes in SecA. Our results suggest a mechanism for nascent substrate protein recognition.

【 授权许可】

CC BY