Cloning and expression of an Arabidopsis thaliana cDNA encoding a monofunctional aspartate kinase homologous to the lysine-sensitive enzyme of Escherichia coli

• Published in: Plant molecular biology Vol. 34; no. 2; pp. 287 - 294
• Main Authors: Tang, G. (Weizmann Inst. of Science, Rehovot (Israel). Dept. of Plant Genetics), Zhu-Shimoni, J.X, Amir, R, Ben-Tzvi Zchori, I, Galili, G
• Format: Journal Article
• Language: English
• Published: Netherlands Springer Nature B.V 01.05.1997
• Subjects: ADN; Amino Acid Sequence; Amino acids; Arabidopsis - enzymology; Arabidopsis - genetics; ARABIDOPSIS THALIANA; Aspartate Kinase - chemistry; Aspartate Kinase - drug effects; Aspartate Kinase - genetics; Bacteria; Bacterial Proteins - drug effects; Bacterial Proteins - genetics; Base Sequence; Cloning; CODE GENETIQUE; CODIGO GENETICO; DNA; DNA, Complementary - biosynthesis; DNA, Complementary - isolation & purification; E coli; Escherichia coli; Escherichia coli - enzymology; Escherichia coli - genetics; EXPRESION GENICA; EXPRESSION DES GENES; GENE; GENE EXPRESSION; Gene Expression Regulation, Plant - drug effects; GENES; Genes, Plant - drug effects; GENETIC CODE; ISOENZIMAS; ISOENZYME; ISOENZYMES; Isoenzymes - chemistry; Isoenzymes - drug effects; Isoenzymes - genetics; LISINA; LYSINE; Lysine - pharmacology; Molecular Sequence Data; Multigene Family; Plant Proteins - drug effects; Plant Proteins - genetics; Proteins; Sequence Homology, Amino Acid; THREONINE; TRANSFERASAS; TRANSFERASE; TRANSFERASES; TREONINA
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1023/A:1005849228945

As in many bacterial species, the first enzymatic reaction of the aspartate-family pathway in plants is mediated by several isozymes of aspartate kinase (AK) that are subject to feedback inhibition by the end-product amino acids lysine or threonine. So far, only cDNAs and genes encoding threonine-sensitive AKs have been cloned from plants. These were all shown to encode polypeptides containing two linked activities, namely AK and homoserine dehydrogenase (HSD), similar to the Escherichia coli thrA gene encoding a threonine-sensitive bifunctional AK/HSD isozyme. In the present report, we describe the cloning of a new Arabidopsis thaliana cDNA that is relatively highly homologous to the E. coli lysC gene encoding the lysine-sensitive AK isozyme. Moreover, similar to the bacterial lysine-sensitive AK, the polypeptide encoded by the present cDNA is monofunctional and does not contain and HSD domain. These observations imply that our cloned cDNA encodes a lysine-sensitive AK. Southern blot hybridization detected a single gene highly homologous to the present cDNA, plus an additional much less homologous gene. This was confirmed by the independent cloning of an additional Arabidopsis cDNA encoding a lysine-sensitive AK (see accompanying paper). Northern blot analysis suggested that the gene encoding this monofunctional AK cDNA is abundantly expressed in most if not all tissues of Arabidopsis.