HmuP is a coactivator of Irr-dependent expression of heme utilization genes in Bradyrhizobium japonicum.

ABSTRACT: Utilization of heme as an iron source by Bradyrhizobium japonicum involves induction of the outer membrane heme receptor gene hmuR and other genes within the heme utilization locus. Here, we discovered the hmuP gene located upstream of hmuR and transcribed divergently from it along with hmuTUV. hmuP encodes a small protein that accumulated under iron limitation and is transcriptionally controlled by the global iron-responsive regulator Irr, as were all genes within the heme utilization locus. Cross-linking and immunoprecipitation experiments showed that Irr occupies the hmuR-hmuP promoter in vivo. An hmuP mutant did not grow on heme as an iron source, but retained the ability to use ferric chloride. Correspondingly, induction of hmuR mRNA under iron limitation was severely diminished in an

SUBMITTER: Escamilla-Hernandez R 

PROVIDER: S-EPMC3370842 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature