Format

Send to

Choose Destination
See comment in PubMed Commons below
J Bacteriol. 2004 Dec;186(23):7896-904.

Ralstonia solanacearum iron scavenging by the siderophore staphyloferrin B is controlled by PhcA, the global virulence regulator.

Author information

1
Department of Plant Pathology, University of Georgia, Athens, GA 30602, USA.

Abstract

PhcA is a transcriptional regulator that activates expression of multiple virulence genes in the plant pathogen Ralstonia solanacearum. Relative to their wild-type parents, phcA mutants overproduced iron-scavenging activity detected with chrome azurol S siderophore detection medium. Transposon mutagenesis of strain AW1-PC (phcA1) generated strain GB6, which was siderophore negative but retained weak iron-scavenging activity. The ssd gene inactivated in GB6 encodes a protein similar to group IV amino acid decarboxylases, and its transcription was repressed by iron(III) and PhcA. ssd is the terminal gene in a putative operon that also appears to encode three siderophore synthetase subunits, a integral membrane exporter, and three genes with no obvious role in siderophore production. A homologous operon was found in the genomes of Ralstonia metallidurans and Staphylococcus aureus, both of which produce the polycarboxylate siderophore staphyloferrin B. Comparison of the siderophores present in culture supernatants of R. solanacearum, R. metallidurans, and Bacillus megaterium using chemical tests, a siderophore utilization bioassay, thin-layer chromatography, and mass spectroscopy indicated that R. solanacearum produces staphyloferrin B rather than schizokinen as was reported previously. Inactivation of ssd in a wild-type AW1 background resulted in a mutant almost incapable of scavenging iron but normally virulent on tomato plants. AW1 did not produce siderophore activity when cultured in tomato xylem sap, suggesting that the main location in tomato for R. solanacearum during pathogenesis is iron replete.

PMID:
15547261
PMCID:
PMC529077
DOI:
10.1128/JB.186.23.7896-7904.2004
[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Support Center