title: Rhizobiales-like Phosphatase 2 from Arabidopsis thaliana Is a Novel Phospho-tyrosine-specific Phospho-protein Phosphatase (PPP) Family Protein Phosphatase.
abstract: Cellular signaling through protein tyrosine phosphorylation is well established in mammalian cells. Although lacking the classic tyrosine kinases present in humans, plants have a tyrosine phospho-proteome that rivals human cells. Here we report a novel plant tyrosine phosphatase from Arabidopsis thaliana (AtRLPH2) that, surprisingly, has the sequence hallmarks of a phospho-serine/threonine phosphatase belonging to the PPP family. Rhizobiales/Rhodobacterales/Rhodospirillaceae-like phosphatases (RLPHs) are conserved in plants and several other eukaryotes, but not in animals. We demonstrate that AtRLPH2 is localized to the plant cell cytosol, is resistant to the classic serine/threonine phosphatase inhibitors okadaic acid and microcystin, but is inhibited by the tyrosine phosphatase inhibitor orthovanadate and is particularly sensitive to inhibition by the adenylates, ATP and ADP. AtRLPH2 displays remarkable selectivity toward tyrosine-phosphorylated peptides versus serine/threonine phospho-peptides and readily dephosphorylates a classic tyrosine phosphatase protein substrate, suggesting that in vivo it is a tyrosine phosphatase. To date, only one other tyrosine phosphatase is known in plants; thus AtRLPH2 represents one of the missing pieces in the plant tyrosine phosphatase repertoire and supports the concept of protein tyrosine phosphorylation as a key regulatory event in plants.
authors.affiliation: From the Department of Biological Sciences, University of Calgary, Calgary,Alberta T2N 1N4, Canada.
authors.forename: R Glen
authors.initials: RG
authors.lastname: Uhrig
authors.affiliation: From the Department of Biological Sciences, University of Calgary, Calgary,Alberta T2N 1N4, Canada.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Labandera
authors.affiliation: From the Department of Biological Sciences, University of Calgary, Calgary,Alberta T2N 1N4, Canada.
authors.forename: Jamshed
authors.initials: J
authors.lastname: Muhammad
authors.affiliation: From the Department of Biological Sciences, University of Calgary, Calgary,Alberta T2N 1N4, Canada.
authors.forename: Marcus
authors.initials: M
authors.lastname: Samuel
authors.affiliation: From the Department of Biological Sciences, University of Calgary, Calgary,Alberta T2N 1N4, Canada. Electronic address: moorhead@ucalgary.ca.
authors.forename: Greg B
authors.initials: GB
authors.lastname: Moorhead
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D017360:Arabidopsis / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000032:analysis / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000032:analysis / Q000378:metabolism*; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000032:analysis / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D010749:Phosphoprotein Phosphatases; C000609583:RLPH2 protein, Arabidopsis; D017027:Protein Tyrosine Phosphatases
keywords: Arabidopsis thaliana; Phosphoprotein phosphatase; protein phosphatase; protein phosphorylation; protein serine/threonine phosphatase (PSP); serine/threonine phosphatase; tyrosine-protein phosphatase (tyrosine phosphatase)