Horizontally acquired regulatory gene activates ancestral regulatory system to promote Salmonella virulence

摘要: Horizontally acquired genes are typically regulated by ancestral regulators. This regulation enables expression of horizontally to be coordinated with that preexisting genes. Here, we report a singular example the opposite regulation: gene controls an regulator, thereby promoting bacterial virulence. We establish regulatory ssrB is necessary activate system PhoP/PhoQ Salmonella enterica serovar Typhimurium (S. Typhimurium) in mildly acidic pH, which S. experiences inside macrophages. SsrB promotes phoP transcription binding upstream promoter. also increases ugtL promoter region, where it overcomes silencing heat-stable nucleoid structuring protein H-NS, enhancing The largely non-pathogenic species bongori failed pH because lacks both and site target Low Mg2+ activated ssrB-lacking Typhimurium, indicating requirement for activation signal-dependent. By controlling genome, responsible more crucial abilities, including virulence, than currently thought.