Kinetic analysis of lamB mutants suggests the signal sequence plays multiple roles in protein export

J. Stader, S. A. Benson, T. J. Silhavy

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

We have developed a quantitative assay to measure the rate of processing of precursor LamB into mature protein and have used this assay to characterize 10 previously isolated and 3 new lamB signal sequence mutants. The data suggest that the LamB signal sequence serves a complex function. Our assay has revealed five types of signal sequence defect: 1) a strong kinetic defect resulting from alteration of the secondary structure in the putative α-helical region in the hydrophobic core, 2) a strong, or 3) a weak kinetic defect due to placement of a charged residue in the hydrophobic core, 4) decreased synsthesis of LamB, and 5) both had a decrease in synthesis and a strong kinetic defect. The effect of an extragenic suppressor, prlA4 on the rate of processing pLamB containing signal sequence mutations was also examined and compared to the rates in wild-type strains. It was found that prlA4 increases the rate of processing in some, but not all, mutants having a kinetic defect while having no effect on the decreased synthesis seen in mutants of types 4 and 5.

Original languageEnglish (US)
Pages (from-to)15075-15080
Number of pages6
JournalJournal of Biological Chemistry
Volume261
Issue number32
StatePublished - 1986

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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