Redox-tuning of oxidizing disulfide oxidoreductase generates a potent disulfide isomerase

Shinya Sutoh, Yuko Uemura, Yuko Yamaguchi, Asako Kiyotou, Rena Sugihara, Makiko Nagayasu, Mihoko Kurokawa, Koreaki Ito, Naoki Tsunekawa, Michiko Nemoto, Kenji Inagaki, Takashi Tamura

Research output: Contribution to journalArticle

Abstract

Oxidative folding of extracellular proteins is pivotal for the biogenesis of bacterial virulence factors. Escherichia coli DsbA catalyzes disulfide bond formation in extracellular proteins and in multicomponent architectures on the cell surface. The present study assessed the significance of the redox properties of DsbA by exploiting the plaque-forming ability of bacteriophage M13, which specifically recognizes F-pili during infection of the host cell. A library of mutant dsbA genes was constructed by randomizing the dipeptide XX sequence in the active-site redox motif CXXC and then screened for mutants that altered plaque yield and appearance. In total, 24 dsbA mutant alleles produced substantially different degrees of complementation, and one mutant dsbA gene that encodes a CDIC sequence produced over 40-fold more clear plaques than wild type dsbA. The redox potential of purified DsbA [CDIC] was −172 mV, representing a less-oxidizing catalysis than the wild type DsbA (−122 mV), but one that is closer to yeast protein disulfide isomerase (−175 mV). DsbA [CDIC] exhibited a greater ability to refold fully denatured glutathionylated ribonuclease A than the wild type enzyme and a DsbA [CRIC] mutant, which has the same redox potential of −172 mV. Homology modeling and molecular dynamics simulation suggest that the CDIC mutant may have an enlarged substrate-binding cleft near the redox center, which confers kinetic advantages when acting on protein substrates.

Original languageEnglish
Pages (from-to)194-201
Number of pages8
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Volume1867
Issue number3
DOIs
Publication statusPublished - Mar 1 2019

Keywords

  • Disulfide oxidoreductase
  • dsbA
  • F-pili
  • Molecular dynamics
  • Redox motif

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biophysics
  • Biochemistry
  • Molecular Biology

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