The PAS domain‐containing histidine kinase RpfS is a second sensor for the diffusible signal factor of Xanthomonas campestris. Issue 3 (2nd April 2014)

• Record Type: Journal Article
• Authors: An, Shi‐Qi; Allan, John H.; McCarthy, Yvonne; Febrer, Melanie; Dow, J. Maxwell; Ryan, Robert P.
• Is Part Of: Molecular microbiology. Volume 92:Issue 3(2014)
• Page Start: 586
• Page End: 597
• Publication Date: 2014-04-02
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12577
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>A cell–cell signalling system mediated by the fatty acid signal DSF controls the virulence of <italic>X</italic><italic>anthomonas campestris</italic> pv. <italic>campestris</italic> (<italic>Xcc</italic>) to plants. The synthesis and recognition of the DSF signal depends upon different Rpf proteins. DSF signal generation requires RpfF whereas signal perception and transduction depends upon the sensor RpfC and regulator RpfG. Detailed analyses of the regulatory roles of different Rpf proteins have suggested the occurrence of further sensors for DSF. Here we have used a mutagenesis approach coupled with high‐resolution transcriptional analysis to identify XC_2579 (RpfS) as a second sensor for DSF in <italic>Xcc</italic>. RpfS is a complex sensor kinase predicted to have multiple Per/Arnt/Sim (PAS) domains, a histidine kinase domain and a C‐terminal receiver (REC) domain. Isothermal calorimetry showed that DSF bound to the isolated N‐terminal PAS domain with a <italic>K</italic><sub>d</sub> of 1.4 μM. RpfS controlled expression of a sub‐set of genes distinct from those controlled by RpfC to include genes involved in type IV secretion and chemotaxis. Mutation of <italic>XC</italic><italic>_2579</italic> was associated with a reduction in virulence of <italic>Xcc</italic> to Chinese Radish when assayed by leaf spraying but not by leaf inoculation, suggesting a role for RpfS‐controlled factors in the epiphytic phase of the disease cycle.</p> </abstract>