The Enzymology of Protein Translocation across the Escherichia coli Plasma Membrane

William Wickner, Arnold J.M. Driessen, Franz-Ulrich Hartl

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    334 Citations (Scopus)

    Abstract

    Converging physiological, genetic, and biochemical studies have established the salient features of preprotein translocation across the plasma membrane of Escherichia coli. Translocation is catalyzed by two proteins, a soluble chaperone and a membrane-bound translocase. SecB, the major chaperone for export, forms a complex with preproteins. Complex formation inhibits side-reactions such as aggregation and misfolding and aids preprotein binding to the membrane surface. Translocase consists of functionally linked peripheral and integral membrane protein domains. SecA protein, the peripheral membrane domain of translocase, is the primary receptor for the SecB/preprotein complex. SecA hydrolyzes ATP, promoting cycles of translocation, preprotein release, Δµ~H+-dependent translocation, and rebinding of the preprotein. The membrane-embedded domain of translocase is the SecY/E protein. It has, as subunits, the SeeY and SecE polypeptides. The SecY/E protein stabilizes and activates SecA and participates in binding it to the membrane. SecA recognizes the leader domain of preproteins, whereas both SecA and SecB recognize the mature domain. Many proteins translocate without requiring SecB, and some proteins do not need translocase to assemble into the plasma membrane. Translocation is usually followed by endoproteolytic cleavage by leader peptidase. The availability of virtually every pure protein and cloned gene involved in the translocation process makes E. coli the premier organism for the study of translocation mechanisms.
    Original languageEnglish
    Pages (from-to)101-124
    Number of pages24
    JournalAnnual Review of Biochemistry
    Volume60
    Issue number1
    DOIs
    Publication statusPublished - 1991

    Keywords

    • TRANSLOCASE
    • SECRETION
    • TRANSLOCATION ATPASE
    • LEADER PEPTIDE
    • PROTONMOTIVE FORCE
    • MALTOSE-BINDING-PROTEIN
    • SIGNAL RECOGNITION PARTICLE
    • PROTON MOTIVE FORCE
    • POSITIVELY CHARGED RESIDUES
    • AMINO-ACID RESIDUES
    • MITOCHONDRIAL PRECURSOR PROTEINS
    • ENDOPLASMIC-RETICULUM MEMBRANE
    • NASCENT PERIPLASMIC PROTEINS
    • BACTERIAL LEADER PEPTIDASE
    • CYTOPLASMIC MEMBRANE

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