title: A branched-chain amino acid aminotransferase gene isolated from Hordeum vulgare is differentially regulated by drought stress.
abstract: Differential display was used to isolate cDNA clones showing differential expression in response to ABA, drought and cold in barley seedling shoots. One drought-regulated cDNA clone (DD12) was further analyzed and found to encode a branched-chain amino acid aminotransferase (HvBCAT-1). A genomic clone was isolated by probing the Morex BAC library with the cDNA clone DD12 and the structure of Hvbcat-1 was elucidated. The coding region is interrupted by six introns and contains a predicted mitochondrial transit peptide. Hvbcat1 was mapped to chromosome 4H. A comparison was made to rice and Arabidopsis genes to identify conserved structural patterns. Complementation of a yeast (Saccharomyces cerevisiae) double knockout strain revealed that HvBCAT-1 can function as the mitochondrial (catabolic) BCATs in vivo. Transcript levels of Hvbcat-1, increased in response to drought stress. As the first enzyme in the branched-chain amino acid (BCAA) catabolic pathway, HvBCAT-1 might have a role in the degradation of BCAA. Degradation of BCAA could serve as a detoxification mechanism that maintains the pool of free branched-chain amino acids at low and non toxic levels, under drought stress conditions.
authors.affiliation: Dipartimento di Scienze Ambientali, Sez. Genetica e Biotecnologie Ambientali, Università di Parma, Viale G.P. Usberti 11a, 43100 Parma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Malatrasi
authors.forename: M
authors.initials: M
authors.lastname: Corradi
authors.forename: J T
authors.initials: JT
authors.lastname: Svensson
authors.forename: T J
authors.initials: TJ
authors.lastname: Close
authors.forename: M
authors.initials: M
authors.lastname: Gulli
authors.forename: N
authors.initials: N
authors.lastname: Marmiroli
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D000595:Amino Acid Sequence; D000597:Amino Acids, Branched-Chain / Q000378:metabolism; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D003001:Cloning, Molecular; D017124:Conserved Sequence; D003681:Dehydration; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D001467:Hordeum / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D000637:Transaminases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014867:Water / Q000378:metabolism*
chemical_list: D000597:Amino Acids, Branched-Chain; D010937:Plant Growth Regulators; D010940:Plant Proteins; D012333:RNA, Messenger; D014867:Water; D000040:Abscisic Acid; D000637:Transaminases