Open AccessCalcium/calmodulin activation of two divergent glutamate decarboxylases from tobacco
Author(s) -
Dmytro P. Yevtushenko,
Michael D. McLean,
Sriyani Peiris,
Owen R. Van Cauwenberghe,
Barry J. Shelp
Publication year - 2003
Publication title -
journal of experimental botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.616
H-Index - 242
eISSN - 1460-2431
pISSN - 0022-0957
DOI - 10.1093/jxb/erg210
Subject(s) - nicotiana tabacum , biochemistry , calmodulin , glutamate decarboxylase , amino acid , complementary dna , gene , recombinant dna , escherichia coli , open reading frame , decarboxylation , biology , carboxy lyases , chemistry , microbiology and biotechnology , peptide sequence , enzyme , catalysis
Glutamate decarboxylase (GAD, EC 4.1.1.15) catalyses the alpha-decarboxylation of glutamate to produce gamma-aminobutyrate (GABA). The nucleotide sequences of two divergent GADs (designated GAD1 and GAD3) were isolated from a Nicotiana tabacum L. cv. Samsun NN leaf cDNA library. Open reading frames indicated that GAD1 encodes a polypeptide of 496 amino acids and has greater than 99% identity with known tobacco GADs, whereas GAD3 encodes a polypeptide of 491 amino acids and has about 14% divergence from known tobacco GADs. Genomic DNA analysis suggested that there are at least four tobacco GAD genes, existing in pairs of highly identical genes. An in vitro assay at pH 7.3 revealed that activities of the recombinant proteins, after isolation from Escherichia coli and partial purification by nickel-affinity chromatography, are 57-133 times the control levels in the presence of 0.5 mM calcium and 0.2 micro M bovine calmodulin.
Accelerating Research
Robert Robinson Avenue,
Oxford Science Park, Oxford
OX4 4GP, United Kingdom
Address
John Eccles HouseRobert Robinson Avenue,
Oxford Science Park, Oxford
OX4 4GP, United Kingdom