branched-chain amino acid aminotransferase gene isolated from Hordeum vulgare is differentially regulated by drought stress

• Published in: Theoretical and applied genetics 2006-10, Vol.113 (6), p.965-976
• Main Authors: Malatrasi, M, Corradi, M, Svensson, J.T, Close, T.J, Gulli, M, Marmiroli, N
• Format: Article
• Language: English
• Subjects: Abscisic Acid - pharmacology; Amino Acid Sequence; Amino acids; Amino Acids, Branched-Chain - metabolism; Arabidopsis; Biological and medical sciences; Chromosome Mapping; Chromosomes, Plant; Classical genetics, quantitative genetics, hybrids; Cloning, Molecular; Conserved Sequence; Dehydration; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Genetic Complementation Test; Genetics of eukaryotes. Biological and molecular evolution; Hordeum - enzymology; Hordeum - genetics; Hordeum vulgare; Molecular Sequence Data; Oryza sativa; Plant Growth Regulators - pharmacology; Plant Proteins - chemistry; Plant Proteins - genetics; Plant Proteins - metabolism; Pteridophyta, spermatophyta; RNA, Messenger - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Sequence Alignment; Sequence Analysis, Protein; Transaminases - chemistry; Transaminases - genetics; Transaminases - metabolism; Vegetals; Water - metabolism
• ISSN: 0040-5752; 1432-2242
• DOI: 10.1007/s00122-006-0339-6

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.