Characterization of the N-oxygenase AurF from Streptomyces thioletus

Emmanuel Chanco, Yoo Seong Choi, Ning Sun, Michael Vu, Huimin Zhao

Research output: Contribution to journalArticlepeer-review

Abstract

AurF catalyzes the N-oxidation of p-aminobenzoic acid to p-nitrobenzoic acid in the biosynthesis of the antibiotic aureothin. Here we report the characterization of AurF under optimized conditions to explore its potential use in biocatalysis. The pH optimum of the enzyme was established to be 5.5 using phenazine methosulfate (PMS)/NADH as the enzyme mediator system, showing ∼10-fold higher activity than previous reports in literature. Kinetic characterization at optimized conditions give a Km of 14.7 ± 1.1 μM, a kcat of 47.5 ± 5.4 min-1 and a kcat/Km of 3.2 ± 0.4 μM-1 min-1. PMS/NADH and the native electron transfer proteins showed significant formation of the p-hydroxylaminobenzoic acid intermediate, however H2O2 produced mostly p-nitrobenzoic acid. Alanine scanning identified the role of important active site residues. The substrate specificity of AurF was examined and rationalized based on the protein crystal structure. Kinetic studies indicate that the Km is the main determinant of AurF activity toward alternative substrates.

Original languageEnglish (US)
Pages (from-to)5569-5577
Number of pages9
JournalBioorganic and Medicinal Chemistry
Volume22
Issue number20
DOIs
StatePublished - Oct 15 2014

Keywords

  • AurF
  • Biocatalysis
  • Diiron monooxygenase
  • Electron transfer
  • N-Oxygenation

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry
  • Molecular Biology
  • Molecular Medicine
  • Organic Chemistry
  • Drug Discovery
  • Pharmaceutical Science

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