Coordinating assembly and export of complex bacterial proteins

Jack, Rachael L., Buchanan, Grant, Dubini, Alexandra, Hatzixanthis, Kostas, Palmer, Tracy and Sargent, Frank (2004) Coordinating assembly and export of complex bacterial proteins. The EMBO Journal, 23 (20). pp. 3962-3972. ISSN 1460-2075

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The Escherichia coli twin-arginine protein transport (Tat) system is a molecular machine dedicated to the translocation of fully folded substrate proteins across the energy-transducing inner membrane. Complex cofactor-containing Tat substrates, such as the model (NiFe) hydrogenase-2 and trimethylamine N-oxide reductase (TorA) systems, acquire their redox cofactors prior to export from the cell and require to be correctly assembled before transport can proceed. It is likely, therefore, that cellular mechanisms exist to prevent premature export of immature substrates. Using a combination of genetic and biochemical approaches including gene knockouts, signal peptide swapping, complementation, and site-directed mutagenesis, we highlight here this crucial ‘proofreading’ or ‘quality control’ activity in operation during assembly of complex endogenous Tat substrates. Our experiments successfully uncouple the Tat transport and cofactor-insertion activities of the TorA-specific chaperone TorD and demonstrate unequivocally that TorD recognises the TorA twin-arginine signal peptide. It is proposed that some Tat signal peptides operate in tandem with cognate binding chaperones to orchestrate the assembly and transport of complex enzymes.

Item Type: Article
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Pure Connector
Date Deposited: 23 Sep 2016 23:31
Last Modified: 06 Mar 2023 15:30
DOI: 10.1038/sj.emboj.7600409

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