title: A rhizosphere fungus enhances Arabidopsis thermotolerance through production of an HSP90 inhibitor.
abstract: The molecular chaperone HEAT SHOCK PROTEIN90 (HSP90) is essential for the maturation of key regulatory proteins in eukaryotes and for the response to temperature stress. Earlier, we have reported that fungi living in association with plants of the Sonoran desert produce small molecule inhibitors of mammalian HSP90. Here, we address whether elaboration of the HSP90 inhibitor monocillin I (MON) by the rhizosphere fungus Paraphaeosphaeria quadriseptata affects plant HSP90 and plant environmental responsiveness. We demonstrate that MON binds Arabidopsis (Arabidopsis thaliana) HSP90 and can inhibit the function of HSP90 in lysates of wheat (Triticum aestivum) germ. MON treatment of Arabidopsis seedlings induced HSP101 and HSP70, conserved components of the stress response. Application of MON, or growth in the presence of MON, allowed Arabidopsis wild type but not AtHSP101 knockout mutant seedlings to survive otherwise lethal temperature stress. Finally, cocultivation of P. quadriseptata with Arabidopsis enhanced plant heat stress tolerance. These data demonstrate that HSP90-inhibitory compounds produced by fungi can influence plant growth and responses to the environment.
authors.affiliation: FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA.
authors.forename: Catherine A
authors.initials: CA
authors.lastname: McLellan
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Turbyville
authors.forename: E M Kithsiri
authors.initials: EM
authors.lastname: Wijeratne
authors.forename: Arthur
authors.initials: A
authors.lastname: Kerschen
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Vierling
authors.forename: Christine
authors.initials: C
authors.lastname: Queitsch
authors.forename: Luke
authors.initials: L
authors.lastname: Whitesell
authors.forename: A A Leslie
authors.initials: AA
authors.lastname: Gunatilaka
mesh_terms: D000222:Adaptation, Physiological; D017360:Arabidopsis / Q000378:metabolism / Q000382:microbiology*; D001203:Ascomycota / Q000378:metabolism*; D015870:Gene Expression; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006358:Hot Temperature; D007783:Lactones / Q000378:metabolism* / Q000494:pharmacology; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology*; D013559:Symbiosis / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism
chemical_list: C115569:HSP101 protein, plant; D018841:HSP90 Heat-Shock Proteins; D007783:Lactones; D010940:Plant Proteins; D014157:Transcription Factors; C444505:monocillin I