title: The unconventional P-loop NTPase OsYchF1 and its regulator OsGAP1 play opposite roles in salinity stress tolerance.
abstract: YchF proteins are a group of mysterious but ubiquitous unconventional G-proteins found in all kingdoms of life except Archaea. Their functions have been documented in microorganisms, protozoa and human, but those of plant YchF homologues are largely unknown. Our group has previously shown that OsYchF1 and its interacting protein, OsGAP1, play opposite roles in plant defense responses. OsGAP1 was found to stimulate the GTPase/ATPase activities of OsYchF1 and regulate its subcellular localization. In this report, we demonstrate that both OsYchF1 and OsGAP1 are localized mainly in the cytosol under NaCl treatment. The ectopic expression of OsYchF1 in transgenic Arabidopsis thaliana leads to reduced tolerance towards salinity stress, while the ectopic expression of OsGAP1 has the opposite effect. Similar results were also obtained with the Arabidopsis homologues, AtYchF1 and AtGAP1, by using AtGAP1 overexpressors and underexpressors, as well as an AtYchF1-knockdown mutant. OsYchF1 and OsGAP1 also exhibit highly significant effects on salinity-induced oxidative stress tolerance. The expression of OsYchF1 suppresses the anti-oxidation enzymatic activities and increases lipid peroxidation in transgenic Arabidopsis, and leads to the accumulation of reactive oxygen species (ROS) in tobacco BY-2 cells, while the ectopic expression of OsGAP1 has the opposite effects in these two model systems.
authors.affiliation: Center for Soybean Research, State Key Laboratory of Agrobiotechnology & School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
authors.forename: Ming-Yan
authors.initials: MY
authors.lastname: Cheung
authors.forename: Man-Wah
authors.initials: MW
authors.lastname: Li
authors.forename: Yuk-Lin
authors.initials: YL
authors.lastname: Yung
authors.forename: Chao-Qing
authors.initials: CQ
authors.lastname: Wen
authors.forename: Hon-Ming
authors.initials: HM
authors.lastname: Lam
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000648:ultrastructure; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006801:Humans; D043583:Nucleoside-Triphosphatase / Q000378:metabolism*; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D010084:Oxidation-Reduction / Q000187:drug effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D054712:Salinity; D055049:Salt Tolerance / Q000187:drug effects; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D000975:Antioxidants; D010940:Plant Proteins; D012965:Sodium Chloride; D043583:Nucleoside-Triphosphatase
keywords: abiotic stress; oxidative stress; unconventional G-proteins