title: Pseudomonas syringae hijacks plant stress chaperone machinery for virulence.
abstract: Plant heat shock protein Hsp70 is the major target of HopI1, a virulence effector of pathogenic Pseudomonas syringae. Hsp70 is essential for the virulence function of HopI1. HopI1 directly binds Hsp70 through its C-terminal J domain and stimulates Hsp70 ATP hydrolysis activity in vitro. In plants, HopI1 forms large complexes in association with Hsp70 and induces and recruits cytosolic Hsp70 to chloroplasts, the site of HopI1 localization. Deletion of a central P/Q-rich repeat region disrupts HopI1 virulence but not Hsp70 interactions or association with chloroplasts. Thus, HopI1 must not only bind Hsp70 through its J domain, but likely actively affects Hsp70 activity and/or specificity. At high temperature, HopI1 is dispensable for P. syringae pathogenicity, unless excess Hsp70 is provided. A working hypothesis is that Hsp70 has a defense-promoting activity(s) that HopI1 or high temperature can subvert. Enhanced susceptibility of Hsp70-depleted plants to nonpathogenic strains of P. syringae supports a defense-promoting role for Hsp70.
authors.affiliation: Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637, USA. jjelensk@uchicago.edu
authors.forename: Joanna
authors.initials: J
authors.lastname: Jelenska
authors.forename: Jodocus A
authors.initials: JA
authors.lastname: van Hal
authors.forename: Jean T
authors.initials: JT
authors.lastname: Greenberg
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D017360:Arabidopsis / Q000378:metabolism* / Q000382:microbiology*; D018556:Crops, Agricultural / Q000378:metabolism / Q000382:microbiology; D003600:Cytosol / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006868:Hydrolysis; D007113:Immunity, Innate / Q000276:immunology; D046912:Multiprotein Complexes / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D044224:Pseudomonas syringae / Q000472:pathogenicity*; D013312:Stress, Physiological; D013696:Temperature; D014026:Nicotiana / Q000378:metabolism / Q000382:microbiology; D014774:Virulence; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D018840:HSP70 Heat-Shock Proteins; D046912:Multiprotein Complexes; D010940:Plant Proteins; D037521:Virulence Factors; D000255:Adenosine Triphosphate