title: The C-terminal extension of PrhG impairs its activation of hrp expression and virulence in Ralstonia solanacearum.
abstract: Ralstonia solanacearum is the second most destructive bacterial plant pathogens worldwide and HrpG is the master regulator of its pathogenicity. PrhG is a close paralogue of HrpG and both belong to OmpR/PhoB family of two-component response regulators. Despite a high similarity (72% global identity and 96% similarity in helix-loop-helix domain), they display distinct roles in pathogenicity. HrpG is necessary for the bacterial growth in planta and pathogenicity, while PrhG is dispensable for bacterial growth in planta and contributes little to pathogenicity. The main difference between HrpG and PrhG is the 50-amino-acid-long C-terminal extension in PrhG (amino-acid residues 230-283), which is absent in HrpG. When this extension is deleted, truncated PrhGs (under the control of its native promoter) allowed complete recovery of bacterial growth in planta and wild-type virulence of hrpG mutant. This novel finding demonstrates that the extension region in PrhG is responsible for the functional difference between HrpG and PrhG, which may block the binding of PrhG to target promoters and result in impaired activation of hrp expression by PrhG and reduced virulence of R. solanacearum.
authors.affiliation: Research Center of Bioenergy and Bioremediation, Southwest University, BeiBei District, Chongqing 400715, China bioyongzhang@gmail.com.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Research Center of Bioenergy and Bioremediation, Southwest University, BeiBei District, Chongqing 400715, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Luo
authors.affiliation: Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan.
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Hikichi
authors.affiliation: Laboratory of Plant Pathology and Biotechnology, Kochi University, Nankoku, Kochi 783-8502, Japan.
authors.forename: Akinori
authors.initials: A
authors.lastname: Kiba
authors.affiliation: Research Center of Bioenergy and Bioremediation, Southwest University, BeiBei District, Chongqing 400715, China.
authors.forename: Igarashi
authors.initials: I
authors.lastname: Yasuo
authors.affiliation: Research Institute of Molecular Genetics, Kochi University, Nankoku, Kochi 783-8502, Japan.
authors.forename: Kouhei
authors.initials: K
authors.lastname: Ohnishi
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D018551:Solanum lycopersicum / Q000382:microbiology; D009154:Mutation; D010641:Phenotype; D010935:Plant Diseases / Q000382:microbiology*; D043368:Ralstonia solanacearum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity*; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D014157:Transcription Factors
keywords: HrpG and PrhG; Ralstonia solanacearum; type III secretion system