Sandbox Reserved 344: Difference between revisions
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=Introduction= | =Introduction= | ||
The response regulator PhoP from the OmpR/PhoB family of two-component | The response regulator PhoP from the OmpR/PhoB family of two-component systems is responsible for initiating the cellular response to the extracellular concentration of Mg2+ of certain gram-negative bacteria such as ''Escherichia coli'' and ''Salmonella enterica''. A drop in Mg2+ concentration is an indicator to the pathogenic bacteria that it has entered a host cell and needs to react correspondingly. The histidine protein kinase, PhoQ, spanning the inner membrane of the bacteria, senses the lowered Mg2+ concentration and phosphorylates the cytosolic PhoP. PhoP sets a signal cascade in motion, affecting other two component signalling systems and directly regulating gene expression by binding to PhoP boxes on the DNA. PhoP consists of a regulatory domain and an effector domain.<ref name = "Bachh2007"> PMID:17545283</ref><ref name = "Groisman"> PMID:11222580</ref> | ||
Gene regulation is achieved by the increased affinity of the homodimer to the PhoP box, a tandem repeat promoter. The response is organism specific but generally involves virulence and the survival in an environment with low Mg2+ concentration. | Gene regulation is achieved by the increased affinity of the homodimer to the PhoP box, a tandem repeat promoter. The response is organism specific but generally involves virulence and the survival in an environment with low Mg2+ concentration. | ||