title: MAP kinase phosphatase 1 harbors a novel PTS1 and is targeted to peroxisomes following stress treatments.
abstract: In Arabidopsis thaliana, twenty mitogen-activated protein kinases (MAPKs/MPKs) are regulated by five MAP kinase phosphatases (MKPs). Arabidopsis MKP1 has an important role in biotic, abiotic and genotoxic stresses and has been shown to interact with and negatively regulate specifically MPK3 and MPK6. MKP1 has been reported to have a role in negative regulation of reactive oxygen species (ROS) and salicylic acid (SA) production. As essential organelles involved in production of ROS and SA, peroxisomes could possibly be an important compartment for MKP1 activity, however MKP1 was previously reported to be cytosolic. By screening Arabidopsis protein phosphatases for peroxisomal targeting signal 1 (PTS1), we identified MKP1 as a putative peroxisomal protein. Arabidopsis MKP1 was found to harbor a non-canonical PTS1-like tripeptide (Ser-Ala-Leu>) that is conserved in MKP1 orthologs. We show experimentally that the C-terminal Ser-Ala-Leu> can function as a novel PTS1, and alanine in position -2, adds more relaxation to the plant PTS1 motif. The full-length MKP1 remained in the cytosol when transiently expressed in Arabidopsis mesophyll protoplasts under standard conditions. When different biotic and abiotic stresses were applied to mesophyll protoplasts, the full length protein changed its targeting to unidentified organelle-like structures that subsequently fused with peroxisomes. Our results identify MKP1 as a protein dually targeted to cytosol and peroxisomes. The finding that MKP1 targets peroxisomes by a non-canonical PTS1 under stressful conditions highlights the complexity of peroxisomal targeting mechanism.
authors: University of Stavanger, Centre for Organelle Research, Faculty of Science and Technology, N-4036 Stavanger, Norway. Electronic address: amr.kataya@uis.no.
authors: Amr R A
authors: AR
authors: Kataya
authors: University of Stavanger, Centre for Organelle Research, Faculty of Science and Technology, N-4036 Stavanger, Norway.
authors: Edit
authors: E
authors: Schei
authors: University of Stavanger, Centre for Organelle Research, Faculty of Science and Technology, N-4036 Stavanger, Norway. Electronic address: Cathrine.lillo@uis.no.
authors: Cathrine
authors: C
authors: Lillo
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D017124:Conserved Sequence; D003600:Cytosol / Q000378:metabolism; D005408:Flagellin / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D018384:Oxidative Stress / Q000187:drug effects; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D020675:Peroxisomes / Q000187:drug effects / Q000378:metabolism*; D021382:Protein Sorting Signals; D021381:Protein Transport / Q000187:drug effects; D017027:Protein Tyrosine Phosphatases; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D010455:Peptides; D021382:Protein Sorting Signals; D005408:Flagellin; D012965:Sodium Chloride; D020928:Mitogen-Activated Protein Kinases; C499612:MKP1 protein, Arabidopsis; D017027:Protein Tyrosine Phosphatases
keywords: Arabidopsis thaliana; MAP kinase signaling; MKP1; Peroxisomes; Protein phosphatase