Proteolytic processing of Escherichia coli twin-arginine signal peptides by LepB

Iris Luke, Jennifer I. Handford, Tracy Palmer, Frank Sargent

    Research output: Contribution to journalArticlepeer-review

    50 Citations (Scopus)

    Abstract

    The twin-arginine translocation (Tat) apparatus is a protein targeting system found in the cytoplasmic membranes of many prokaryotes. Substrate proteins of the Tat pathway are synthesised with signal peptides bearing SRRxFLK 'twin-arginine' amino acid motifs. All Tat signal peptides have a common tripartite structure comprising a polar N-terminal region, followed by a hydrophobic region of variable length and a polar C-terminal region. In Escherichia coli, Tat signal peptides are proteolytically cleaved after translocation. The signal peptide C-terminal regions contain conserved AxA motifs, which are possible recognition sequences for leader peptidase I (LepB). In this work, the role of LepB in Tat signal peptide processing was addressed directly. Deliberate repression of lepB expression prevented processing of all Tat substrates tested, including SufI, AmiC, and a TorA-23K reporter protein. In addition, electron microscopy revealed gross defects in cell architecture and membrane integrity following depletion of cellular LepB protein levels.

    Original languageEnglish
    Pages (from-to)919-925
    Number of pages7
    JournalArchives of Microbiology
    Volume191
    Issue number12
    DOIs
    Publication statusPublished - Dec 2009

    Keywords

    • Escherichia coli
    • Tat protein transport pathway
    • Signal peptidase I
    • LepB protein
    • OUTER-MEMBRANE
    • EXPORT PATHWAY
    • PROTEIN TRANSLOCATION
    • CELL-ENVELOPE
    • EXPRESSION
    • INTEGRITY
    • PROMOTER
    • VECTORS
    • SYSTEM
    • OPERON

    Cite this