1887

Abstract

The ubiquitous plant pathogen attaches efficiently to plant tissues and abiotic surfaces and can form complex biofilms. A genetic screen for mutants unable to form biofilms on PVC identified disruptions in a homologue of the gene. ExoR is a predicted periplasmic protein, originally identified in , but widely conserved among alphaproteobacteria. Disruptions in the gene result in severely compromised attachment to abiotic surfaces under static and flow conditions, and to plant tissues. These mutants are hypermucoid due to elevated production of the exopolysaccharide succinoglycan, via derepression of the genes that direct succinoglycan synthesis. In addition, mutants have lost flagellar motility, do not synthesize detectable flagellin and are diminished in flagellar gene expression. The attachment deficiency is, however, complex and not solely attributable to succinoglycan overproduction or motility disruption. ExoR can function independently of the ChvG–ChvI two component system, implicated in ExoR-dependent regulation in . Mutations that suppress the motility defect suggest a branched regulatory pathway controlling succinoglycan synthesis, motility and biofilm formation.

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2010-09-01
2019-10-23
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