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

TY - JOUR

T1 - Proteolytic processing of Escherichia coli twin-arginine signal peptides by LepB

A1 - Luke,Iris

A1 - Handford,Jennifer I.

A1 - Palmer,Tracy

A1 - Sargent,Frank

AU - Luke,Iris

AU - Handford,Jennifer I.

AU - Palmer,Tracy

AU - Sargent,Frank

PY - 2009/12

Y1 - 2009/12

N2 - <p>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.</p>

AB - <p>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.</p>

KW - Escherichia coli

KW - Tat protein transport pathway

KW - Signal peptidase I

KW - LepB protein

KW - OUTER-MEMBRANE

KW - EXPORT PATHWAY

KW - PROTEIN TRANSLOCATION

KW - CELL-ENVELOPE

KW - EXPRESSION

KW - INTEGRITY

KW - PROMOTER

KW - VECTORS

KW - SYSTEM

KW - OPERON

U2 - 10.1007/s00203-009-0516-5

DO - 10.1007/s00203-009-0516-5

M1 - Article

JO - Archives of Microbiology

JF - Archives of Microbiology

SN - 0302-8933

IS - 12

VL - 191

SP - 919

EP - 925

ER -