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

DOI: 10.7554/eLife.48385 DOI Help

Authors: Mohammed Jamshad (University of Birmingham) , Timothy J. Knowles (University of Birmingham) , Scott A. White (University of Birmingham) , Douglas G Ward (University of Birmingham) , Fiyaz Mohammed (University of Birmingham) , Kazi Fahmida Rahman (University of Birmingham) , Max Wynne (University of Birmingham) , Gareth W. Hughes (University of Birmingham) , G√ľnter Kramer (German Cancer Research Center (DKFZ), ZMBH-DKFZ Alliance) , Bernd Bukau (German Cancer Research Center (DKFZ), ZMBH-DKFZ Alliance) , Damon Huber (University of Birmingham)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Elife , VOL 8

State: Published (Approved)
Published: June 2019
Diamond Proposal Number(s): 10369

Open Access Open Access

Abstract: In 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.

Subject Areas: Biology and Bio-materials


Instruments: I02-Macromolecular Crystallography

Documents:
elife-48385-v2.pdf

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