Secretion and degradation of mutant leucine‐specific binding protein molecules containing C‐terminal deletions

Robert Landick, James R. Duncan, Bruce R. Copeland, Penelope M. Nazos, Dale L. Oxender

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

The leucine‐specific binding protein (LS‐BP), a periplasmic component of the Escherichia coli high‐affinity leucine transport system, is initially synthesized in a precursor form with a 23 amino acid N‐terminal leader sequence that is removed during secretion of the protein into the periplasm. Using in vitro mutagenesis, deletion mutants of the LS‐BP gene have been constructed with altered or missing amino acid sequences in the C‐terminal portion of the protein. These altered binding proteins exhibited normal processing and secretion but were rapidly degraded in the periplasmic space. In the presence of an uncoupler of the transmembrane potential (CCCP) the precursor forms accumulated in the membrane and were protected from degradation. The altered binding proteins also were secreted by spheroplasts of E coli, after which they were easily detected.

Original languageEnglish
Pages (from-to)331-344
Number of pages14
JournalJournal of cellular biochemistry
Volume24
Issue number4
DOIs
StatePublished - 1984
Externally publishedYes

Keywords

  • degradation
  • leucine binding protein
  • membrane potential
  • periplasmic proteins
  • processing
  • protein secretion
  • proteolysis
  • site‐directed mutagenesis

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