Identification and role in virulence of putative iron acquisition genes from Corynebacterium pseudotuberculosis

Abstract

Four genes, fagA, B, C and D, encoding products with 32^47% identity to proteins involved in bacterial iron uptake systems, were identified immediately downstream of the Corynebacterium pseudotuberculosis phospholipase D gene. L-Galactosidase assays on a C. pseudotuberculosis strain carrying a fagA-lacZ fusion indicated that the putative fagABC operon was poorly expressed in iron-rich media. However, similar experiments in iron-limited media resulted in an approximately three-fold increase in L-galactosidase activity, suggesting that this operon is regulated by iron in vitro. Although no defect in iron utilization could be determined for a C. pseudotuberculosis fagB(C) mutant in vitro, this mutant showed reduced virulence compared to wild-type in a goat model of caseous lymphadenitis. Thus, expression of the fag genes in the host appears to contribute to virulence. ß

Corynebacterium pseudotuberculosis: microbiology, biochemical properties, pathogenesis and molecular studies of virulence

“…They were designated as Fe acquisition genes (fag) A, B, C and D. Since C. pseudotuberculosis is an intracellular pathogen, this bacterium must be able to acquire iron from an environment in which this nutrient is scarce. Although there was no alteration in the utilization of iron by a fagB(C) mutant in vitro, this mutant had a decreased ability to survive and to cause abscesses in experimentally-infected goats [9].…”

“…Recently, it has been proposed that a putative C. pseudotuberculosis iron uptake gene cluster has a role in its virulence [9]. The four genes in this putative operon were identified downstream from the pld gene.…”

“…The ability of the fag genes to be induced by limited iron was studied by transcriptional fusions with the lacZ reporter gene, followed by an assay for β-galactosidase activity [9]. The resultant mutants were grown in both iron-rich and iron-limited media.…”

Analysis of theCorynebacterium diphtheriaeDtxR Regulon: Identification of a Putative Siderophore Synthesis and Transport System That Is Similar to theYersiniaHigh-Pathogenicity Island-Encoded Yersiniabactin Synthesis and Uptake System

“…The frg genes (CD-frg) have homology to the Corynebacterium pseudotuberculosis fag operon, an ABC metal transporter that is iron regulated and required for virulence (7). Mutations in the C. pseudotuberculosis fag genes had no effect on iron transport, and the function of the frg genes in C. diphtheriae is not known.…”

Morel’s Disease and Caseous Lymphadenitis: a Literature Review with Special Reference to Saudi Arabia

“…This process depends on the ability of the agent to infect macrophages, resist phagolysosomes and kill cells, liberating new bacteria and causing necrosis [62]. Other genes such as CP40 and fag A, B, C and D, were described and shown to have an important role in the virulence of Cps [63]. Various molecular techniques have been used to type C. pseudotuberculosis.…”