title: Arabidopsis thaliana AtHAL3: a flavoprotein related to salt and osmotic tolerance and plant growth.
abstract: We have isolated two Arabidopsis thaliana genes, AtHAL3a and AtHAL3b, showing homology with HAL3, a yeast protein which regulates the cell cycle and tolerance to salt stress through inhibition of the PPZ1 type-1 protein phosphatase. Expression of AtHAL3a in yeast hal3 mutants partially complements their LiCl sensitivity, suggesting possible conserved functions between both proteins. AtHAL3a and AtHAL3b are induced by salt stress and AtHAL3a is the most expressed in non-stressed plants, particularly in seeds. In situ hybridization demonstrates enrichment of AtHAL3a mRNA in seed embryos and in the vascular phloem of different plant tissues. AtHAL3 proteins show striking homology with a group of proteins found in fungi, plants and animals and some homology with a large family of prokaryotic flavoproteins. Recombinant AtHAL3a protein purified from Escherichia coli was yellow because it contained a non-covalently bound chromophore revealed as flavin mononucleotide. Trans- genic Arabidopsis plants, with gain of AtHAL3a function, show altered growth rates and improved tolerance to salt and osmotic stress.
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-CSIC, Camino de Vera s/n, 46022 Valencia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Espinosa-Ruiz
authors.forename: J M
authors.initials: JM
authors.lastname: Bellés
authors.forename: R
authors.initials: R
authors.lastname: Serrano
authors.forename: F A
authors.initials: FA
authors.lastname: Culiáñez-MacIà
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins; D018797:Cell Cycle Proteins; D016384:Consensus Sequence; D005656:Fungal Proteins / Q000737:chemistry; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D012639:Seeds; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; C404262:AtHAL3 protein, Arabidopsis; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D010940:Plant Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; C092936:SIS2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins