Location: Emerging Pests and Pathogens ResearchTitle: Identification of the CvsSR regulon in Pseudomonas syringae reveals overlap with the Type-III secretion and AlgU regulons Author
Submitted to: International Conference on Pseudomonas
Publication Type: Abstract Only
Publication Acceptance Date: 6/29/2017
Publication Date: 9/1/2017
Citation: Fishman, M., Stodghill, P., Filiatrault, M.J. 2017. Identification of the CvsSR regulon in Pseudomonas syringae reveals overlap with the Type-III secretion and AlgU regulons. International Conference on Pseudomonas. P5.
Technical Abstract: Pseudomonas syringae pv. tomato DC3000 (Pto) lives epiphytically and endophytically during its infection cycle. Two-component systems (TCSs) and extracytoplasmic function (ECF) sigma factors are used by Pto to sense environmental changes within the leaf apoplast during pathogenesis. The TCS, CvsSR is induced by Ca2+ and is involved in virulence of Pto. We identified the regulon of CvsSR using chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) and with whole transcriptome sequencing (RNA-seq). By combining the results from the ChIP-seq and RNA-seq datasets, we found that CvsR regulates expression of several type-III secretion system (T3SS) effectors and the T3SS regulators, HrpR and HrpS. In addition, the CvsR regulon has significant overlap with the regulon of the ECF sigma factor AlgU, likely due to the fact that CvsR represses transcription of algU. Importantly, we identified a carbonic anhydrase that is directly regulated by CvsSR as a novel virulence factor in Pto. Deletion of this carbonic anhydrase delays the hypersensitive response in Nicotiana benthamiana and effects bacterial competition in Pto, thus providing support that this carbonic anhydrase plays a role in deployment of the T3SS and the type-VI secretion system in Pto. Orthologs of the TCS CvsSR are found in most sequenced pseudomonads and it is possible that these TCSs share similar functions to CvsSR.