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A two‐component system involving an HD‐GYP domain protein links cell–cell signalling to pathogenicity gene expression in Xanthomonas campestris
Author(s) -
Slater Holly,
AlvarezMorales Ariel,
Barber Christine E.,
Daniels Michael J.,
Dow J. Maxwell
Publication year - 2000
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2000.02196.x
Subject(s) - xanthomonas campestris , biology , mutant , response regulator , xanthomonas , gene , operon , signal transduction , two component regulatory system , microbiology and biotechnology , extracellular , hamp domain , protein domain , pas domain , xanthomonas campestris pv. campestris , genetics , transcription factor
The synthesis of extracellular enzymes and extracellular polysaccharide (EPS) in Xanthomonas campestris pv. campestris ( Xcc ) is regulated by a cluster of genes called rpf (for r egulation of p athogenicity f actors). Two of the genes, rpfF and rpfB , have previously been implicated in the synthesis of a diffusible regulatory molecule, DSF. Here, we describe a screen of transposon insertion mutants of Xcc that identified two DSF‐overproducing strains. In each mutant, the gene disrupted is rpfC , which encodes a hybrid two‐component regulatory protein in which the sensor and regulator domains are fused and which contains an additional C‐terminal phosphorelay (HPt) domain. We show that rpfC is in an operon with rpfH and rpfG . The predicted protein RpfG has a regulatory input domain attached to a specialized version of an HD domain, previously suggested to function in signal transduction. The predicted protein RpfH is structurally related to the sensory input domain of RpfC. We show that RpfC and RpfG act positively to regulate the synthesis of extracellular enzymes and EPS, but that RpfC acts negatively to regulate the synthesis of DSF. We propose that RpfGHC is a signal transduction system that couples the synthesis of pathogenicity factors to sensing of environmental signals that may include DSF itself.