1887

Abstract

has multiple systems for iron acquisition, including the use of haem as an iron source. Haem internalization involves the ShmR haem outer membrane receptor and the locus, which participates in haem transport across the cytoplasmic membrane. Previous studies have demonstrated that expression of the gene is negatively regulated by iron through RirA. Here, we identify in a genetic screen for mutants that displayed aberrant control of . The normal induction of in response to iron limitation was lost in the mutant, showing that this gene positively affects expression. Moreover, the HmuP protein is not part of the haemin transporter system. Analysis of gene expression and siderophore production indicates that disruption of does not affect other genes related to the iron-restriction response. Our results strongly indicate that the main function of HmuP is the transcriptional regulation of . Sequence alignment of HmuP homologues and comparison with the NMR structure of CGA009 HmuP protein revealed that certain amino acids localized within predicted -sheets are well conserved. Our data indicate that at least one of the -sheets is important for HmuP activity.

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2010-06-01
2019-10-17
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Primers used in the study [PDF](54 KB)

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Alignment of the last 36 amino acidic residues (HemP domain) of some HmuP homologues from the alpha, beta, gamma, delta and epsilon proteobacteria [PDF](58 KB)

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