PrlA4 prevents the rejection of signal sequence defective preproteins by stabilizing the SecA-SecY interaction during the initiation of translocation

Jeroen P.W. Van Der Wolk, Peter Fekkes, Andre Boorsma, Janet L. Huie, Thomas J. Silhavy, Arnold J.M. Driessen

Research output: Contribution to journalArticle

77 Scopus citations

Abstract

In Escherichia coli, precursor proteins are translocated across the cytoplasmic membrane by translocase. This multisubunit enzyme consists of a preprotein-binding and ATPase domain, SecA, and the SecYEG complex as the integral membrane domain. PrlA4 is a mutant of SecY that enables the translocation of preproteins with a defective, or missing, signal sequence. Inner membranes of the prlA4 strain efficiently translocate Δ8proOmpA, a proOmpA derivative with a non-functional signal sequence. Owing to the signal sequence mutation, Δ8proOmpA binds to the translocase with a lowered affinity and the recognition is not restored by the prlA4 SecY. At the ATP-dependent initiation of translocation, the binding affinity of SecA for SecYEG is lowered causing the premature loss of bound preproteins from the translocase. The prlA4 membranes, however, bind SecA with a much higher affinity than the wild-type, and during initiation, the SecA and preprotein remain bound at the translocation site allowing an improved efficiency of translocation. It is concluded that the prlA4 strain prevents the rejection of defective preproteins from the export pathway by stabilizing SecA at the SecYEG complex.

Original languageEnglish (US)
Pages (from-to)3631-3639
Number of pages9
JournalEMBO Journal
Volume17
Issue number13
DOIs
StatePublished - Jul 1 1998

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

Keywords

  • Proof-reading
  • SecA
  • SecY
  • Signal sequence

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