The Bordetella bronchiseptica nic locus encodes a nicotinic acid degradation pathway and the 6 ‐hydroxynicotinate‐responsive regulator BpsR

This study determined the distribution of the nic genes among Bordetella species and analyzed the regulation of this nicotinic acid degradation system. Transcription of the Bordetella bronchiseptica nicC gene was repressed by the NicR ortholog, BpsR, previously shown to regulate extracellular polysaccharide synthesis genes. nicC expression was derepressed by nicotinic acid or by the first product of the degradation pathway, 6‐hydroxynicotinic acid, which was shown to be the inducer. Results using mutants with either a hyperactivated pathway or an inactivated pathway showed a marked effect on growth on nicotinic acid that indicated this degradation pathway influences NAD biosynthesis. Pathway dysregulation also affected Bordetella BvgAS‐mediated virulence gene regulation, demonstrating that fluctuation of intracellular nicotinic acid pools impacts Bvg phase transition responses. This article is protected by copyright. All rights reserved. Members of the bacterial species Bordetella require nicotinamide, quinolinic acid, or nicotinic acid for biosynthesis of the coenzyme NAD. Our studies examined the regulated expression of Bordetella nic genes that enable nicotinic acid to be degraded for use as a nutritional carbon source. Mutations that altered the activity of the Nic pathway influenced virulence gene transcription and affected growth on nicotinic acid, indicating this degradation pathway impacts NAD biosynthesis.
Source: Molecular Microbiology - Category: Microbiology Authors: Tags: Research Article Source Type: research