title: Molecular mechanisms of two-component system RhpRS regulating type III secretion system in Pseudomonas syringae.
abstract: Pseudomonas syringae uses the two-component system RhpRS to regulate the expression of type III secretion system (T3SS) genes and bacterial virulence. However, the molecular mechanisms and the regulons of RhpRS have yet to be fully elucidated. Here, we show that RhpS functions as a kinase and a phosphatase on RhpR and as an autokinase upon itself. RhpR is phosphorylated by the small phosphodonor acetyl phosphate. A specific RhpR-binding site containing the inverted repeat (IR) motif GTATC-N6-GATAC, was mapped to its own promoter by a DNase I footprint analysis. Electrophoretic mobility shift assay indicated that P-RhpR has a higher binding affinity to the IR motif than RhpR. To identify additional RhpR targets in P. syringae, we performed chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq) and detected 167 enriched loci including the hrpR promoter, suggesting the direct regulation of T3SS cascade genes by RhpR. A genome-wide microarray analysis showed that, in addition to the T3SS cascade genes, RhpR differentially regulates a large set of genes with various functions in response to different growth conditions. Together, these results suggested that RhpRS is a global regulator that allows P. syringae to sense and respond to environmental changes by coordinating T3SS expression and many other biological processes.
authors.affiliation: Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Deng
authors.affiliation: Department of Life Science, Northwest University, Xi'an, Shaanxi 710069, China.
authors.forename: Haihua
authors.initials: H
authors.lastname: Liang
authors.affiliation: Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Chen
authors.affiliation: Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Chuan
authors.initials: C
authors.lastname: He
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Pudong Zhangjiang Hi-Tech Park, Shanghai 201203, China llan@mail.shcnc.ac.cn.
authors.forename: Lefu
authors.initials: L
authors.lastname: Lan
authors.affiliation: College of Life Sciences, Capital Normal University, Beijing 100048, China txy@frontier-ag.com.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Tang
mesh_terms: D000085:Acetates / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems / Q000235:genetics*; D001665:Binding Sites; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D055029:Inverted Repeat Sequences; D009154:Mutation; D010755:Organophosphates / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D044224:Pseudomonas syringae / Q000201:enzymology / Q000235:genetics*; D018085:Regulon
chemical_list: D000085:Acetates; D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D010755:Organophosphates; C011632:acetyl phosphate; D011494:Protein Kinases; D010749:Phosphoprotein Phosphatases