Regulation of the activity of Escherichia coli quinolinate synthase by reversible disulfide-bond formation

Allison H. Saunders, Squire J. Booker

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Quinolinate synthase (NadA) catalyzes a unique condensation reaction between dihydroxyacetone phosphate and iminoaspartate, yielding inorganic phosphate, 2 mol of water, and quinolinic acid, a central intermediate in the biosynthesis of nicotinamide adenine dinucleotide and its derivatives. The enzyme from Escherichia coli contains a C291XXC294XXC 297 motif in its primary structure. Bioinformatics analysis indicates that only Cys297 serves as a ligand to a [4Fe-4S] cluster that is required for turnover. In this report, we show that the two remaining cysteines, Cys291 and Cys294, undergo reversible disulfide-bond formation, which regulates the activity of the enzyme. This mode of redox regulation of NadA appears physiologically relevant, since disulfide-bond formation and reduction are effected by oxidized and reduced forms of E. coli thioredoxin. A midpoint potential of -264 ± 1.77 mV is approximated for the redox couple.

Original languageEnglish (US)
Pages (from-to)8467-8469
Number of pages3
JournalBiochemistry
Volume47
Issue number33
DOIs
StatePublished - Aug 19 2008

All Science Journal Classification (ASJC) codes

  • Biochemistry

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