title: The Arabidopsis aminopeptidase LAP2 regulates plant growth, leaf longevity and stress response.
abstract: Peptidases are known to play key roles in multiple biological processes in all living organisms. In higher plants, the vast majority of putative aminopeptidases remain uncharacterized. In this study, we performed functional and expression analyses of the Arabidopsis LAP2 through cDNA cloning, isolation of T-DNA insertional mutants, characterization of the enzymatic activity, characterization of gene expression and transcriptomics and metabolomics analyses of the mutants. Loss of function of LAP2, one of the 28 aminopeptidases in Arabidopsis, reduced vegetative growth, accelerated leaf senescence and rendered plants more sensitive to various stresses. LAP2 is highly expressed in the leaf vascular tissue and the quiescent center region. Integration of global gene expression and metabolite analyses suggest that LAP2 controlled intracellular amino acid turnover. The mutant maintained free leucine by up-regulating key genes for leucine biosynthesis. However, this influenced the flux of glutamate strikingly. As a result, γ-aminobutyric acid, a metabolite that is derived from glutamate, was diminished in the mutant. Decrements in these nitrogen-rich compounds are associated with morphological alterations and stress sensitivity of the mutant. The results indicate that LAP2 is indeed an enzymatically active aminopeptidase and plays key roles in senescence, stress response and amino acid turnover.
authors.affiliation: Laboratory of Cellular Biochemistry, RIKEN, Wako, Saitama 351-0198, Japan.|Department of Microbiology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand.
authors.forename: Rungaroon
authors.initials: R
authors.lastname: Waditee-Sirisattha
authors.affiliation: Health Technology Research Center, AIST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Shibato
authors.affiliation: Health Technology Research Center, AIST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
authors.forename: Randeep
authors.initials: R
authors.lastname: Rakwal
authors.affiliation: Health Technology Research Center, AIST, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan.
authors.forename: Sophon
authors.initials: S
authors.lastname: Sirisattha
authors.affiliation: Department of System Chemotherapy and Molecular Biosciences, Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Hattori
authors.affiliation: Plant Chemical Biology Research Unit, RIKEN, Wako, Saitama 351-0198, Japan.|JST-PRESTO, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakano
authors.affiliation: Research Institute of Meijo University, Nagoya 468-8502, Japan.
authors.forename: Teruhiro
authors.initials: T
authors.lastname: Takabe
authors.affiliation: Laboratory of Cellular Biochemistry, RIKEN, Wako, Saitama 351-0198, Japan.|Faculty of Pharmaceutical Sciences, Teikyo-Heisei University, Chiba 290-0193, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Tsujimoto
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D007931:Leucyl Aminopeptidase / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D009584:Nitrogen / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010641:Phenotype; D010788:Photosynthesis; D018515:Plant Leaves / Q000254:growth & development*; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012639:Seeds / Q000254:growth & development / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D011994:Recombinant Proteins; D012965:Sodium Chloride; D005680:gamma-Aminobutyric Acid; D007931:Leucyl Aminopeptidase; D009584:Nitrogen