植物病原黄单胞菌退出群体感应生理状态的分子机制和生物学意义

黄单胞菌是一类引起多种作物病害的病原细菌总称.它们利用自身产生的DSF(Diffusible signaling factor)-家族群体感应(quorum sensing,QS)信号分子感应群体密度,调控致病相关基因的表达.当黄单胞菌培养达到对数生长后期时,培养体系中DSF信号分子浓度迅速降低,呈现一种典型的群体感应...

Molecular mechanisms and biological significance of the naturally occurring turnover of DSF-family quorum sensing signal in the phytopathogen Xanthomonas

Xanthomonas represents a range of bacterial species that cause diseases in a variety of crops. They produce and use DSF (Diffusible signaling factor)-family quorum sensing (QS) signal to sense cell population to regulate the expression of virulence genes. At post-logic growth phase, the levels of DSF-family signal decreased rapidly, indicating a naturally occurring signal turnover phenomenon in Xanthomonas. The expression levels of rpfB that encodes a putative fatty acyl CoA ligase, significantly increased at logarithmic growth phase. Deletion of rpfB significantly increased the production of DSF-family signal. Therefore, RpfB is involved in the degradation of DSF-family signals, including Xcc to exit from the quorum sensing phase at post-QS phase. DSF-family signal negatively regulates rpfB expression via rpfC/rpfG two-component signaling system, cyclic di-GMP and the global regulator Clp. The RpfB-dependent naturally DSF turnover system is present in a range of bacterial species, representing a conserved mechanism for QS signal turnover. However, the RpfB-regulated biological roles differ from species to species.