Articles
THE GRRSA-CSR GLOBAL REGULATORY SYSTEM PLAYS A CRITICAL ROLE IN ERWINIA AMYLOVORA VIRULENCE
Article number
1056_33
Pages
207 – 212
Language
English
Abstract
The fire blight pathogen Erwinia amylovora requires a functional type III secretion system (T3SS) and the production of the exopolysaccharide amylovoran to cause disease.
The GacS/GacA two-component system is widely conserved among gammaproteobacteria and is a global regulator of virulence factors.
This system positively regulates non-coding small regulatory RNA csrB, which in turn binds to CsrA, a translational regulator.
In this study, we characterized the grrA, csrB and csrA mutants.
Results showed that the grrA and csrB mutants had similar phenotypes: both were hypermotile, produced a higher amount of amylovoran, and had increased expression of T3SS genes in vivo.
In contrast, the csrA mutant exhibited the opposite phenotypes, including non-motility, no amylovoran production and no expression of T3SS genes.
Furthermore, the csrA mutant did not induce hypersensitive response on non-host tobacco plants neither caused disease on immature pear fruit and apple shoots, indicating that CsrA is a positive regulator of virulence factors.
These findings suggest that negative regulation of virulence by GrrS/GrrA acts through csrB, which likely binds to CsrA, antagonizing its positive effect on T3SS gene expression, flagellar formation and amylovoran production.
The GacS/GacA two-component system is widely conserved among gammaproteobacteria and is a global regulator of virulence factors.
This system positively regulates non-coding small regulatory RNA csrB, which in turn binds to CsrA, a translational regulator.
In this study, we characterized the grrA, csrB and csrA mutants.
Results showed that the grrA and csrB mutants had similar phenotypes: both were hypermotile, produced a higher amount of amylovoran, and had increased expression of T3SS genes in vivo.
In contrast, the csrA mutant exhibited the opposite phenotypes, including non-motility, no amylovoran production and no expression of T3SS genes.
Furthermore, the csrA mutant did not induce hypersensitive response on non-host tobacco plants neither caused disease on immature pear fruit and apple shoots, indicating that CsrA is a positive regulator of virulence factors.
These findings suggest that negative regulation of virulence by GrrS/GrrA acts through csrB, which likely binds to CsrA, antagonizing its positive effect on T3SS gene expression, flagellar formation and amylovoran production.
Publication
Authors
V. Ancona, Y. Zhao
Keywords
RNA binding protein, small non-coding RNA, two-component system
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