Sec-independent protein translocation in Escherichia coli. A distinct and pivotal role for the TatB protein

Frank Sargent, Nicola R. Stanley, Ben C. Berks, Tracy Palmer

    Research output: Contribution to journalArticlepeer-review

    233 Citations (Scopus)

    Abstract

    In Escherichia coli, transmembrane translocation of proteins can proceed by a number of routes. A subset of periplasmic proteins are exported via the Tat pathway to which proteins are directed by N-terminal "transfer peptides" bearing the consensus (S/T)RRXFLK "twin-arginine" motif. The Tat system involves the integral membrane proteins TatA, TatB, TatC, and TatE. Of these, TatA, TatB, and TatE are homologues of the Hcf106 component of the DeltapH-dependent protein import system of plant thylakoids. Deletion of the tatB gene alone is sufficient to block the export of seven endogenous Tat substrates, including hydrogenase-2. Complementation analysis indicates that while TatA and TatE are functionally interchangeable, the TatB protein is functionally distinct. This conclusion is supported by the observation that Helicobacter pylori tatA will complement an E. coli tatA mutant, but not a tatB mutant. Analysis of Tat component stability in various tat deletion backgrounds shows that TatC is rapidly degraded in the absence of TatB suggesting that TatC complexes, and is stabilized by, TatB.
    Original languageEnglish
    Pages (from-to)36073-36082
    Number of pages10
    JournalJournal of Biological Chemistry
    Volume274
    Issue number51
    DOIs
    Publication statusPublished - 1999

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