title: The Arabidopsis oligopeptidases TOP1 and TOP2 are salicylic acid targets that modulate SA-mediated signaling and the immune response.
abstract: Salicylic acid (SA) is a small phenolic molecule with hormonal properties, and is an essential component of the immune response. SA exerts its functions by interacting with protein targets; however, the specific cellular components modulated by SA and critical for immune signal transduction are largely unknown. To uncover cellular activities targeted by SA, we probed Arabidopsis protein microarrays with a functional analog of SA. We demonstrate that thimet oligopeptidases (TOPs) constitute a class of SA-binding enzymes. Biochemical evidence demonstrated that SA interacts with TOPs and inhibits their peptidase activities to various degrees both in vitro and in plant extracts. Functional characterization of mutants with altered TOP expression indicated that TOP1 and TOP2 mediate SA-dependent signaling and are necessary for the immune response to avirulent pathogens. Our results support a model whereby TOP1 and TOP2 act in separate pathways to modulate SA-mediated cellular processes.
authors.affiliation: The Boyce Thompson Institute for Plant Research, Tower Road, Ithaca, NY, 14850, USA.
authors.forename: Magali
authors.initials: M
authors.lastname: Moreau
authors.forename: Timothy
authors.initials: T
authors.lastname: Westlake
authors.forename: Giulio
authors.initials: G
authors.lastname: Zampogna
authors.forename: George
authors.initials: G
authors.lastname: Popescu
authors.forename: Miaoying
authors.initials: M
authors.lastname: Tian
authors.forename: Christos
authors.initials: C
authors.lastname: Noutsos
authors.forename: Sorina
authors.initials: S
authors.lastname: Popescu
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000276:immunology; D029681:Arabidopsis Proteins / Q000235:genetics; D016923:Cell Death; D008666:Metalloendopeptidases / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D057865:Plant Immunity; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020156:Salicylic Acid / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013312:Stress, Physiological
chemical_list: D029681:Arabidopsis Proteins; D010940:Plant Proteins; C089426:RPS2 protein, Arabidopsis; C097421:rps4 protein, plant; D008666:Metalloendopeptidases; C022510:thimet oligopeptidase; D020156:Salicylic Acid
keywords: immunity; programmed cell death; protein microarray; salicylic acid; thimet oligopeptidase