metG gene of Aspergillus nidulans encoding cystathionine beta-lyase: cloning and analysis

• Published in: Current genetics 1999-07, Vol.35 (6), p.638-646
• Main Authors: Sienko, M, Paszewski, A
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; amino acid sequences; Aspergillus nidulans - chemistry; Aspergillus nidulans - enzymology; Aspergillus nidulans - genetics; Aspergillus nidulellus; Base Sequence; cloning; Cloning, Molecular; codon usage; complementary DNA; DNA, Complementary - chemistry; DNA, Complementary - genetics; DNA, Complementary - isolation & purification; DNA, Fungal - chemistry; DNA, Fungal - genetics; DNA, Fungal - isolation & purification; genbank/u28383; gene expression; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Fungal; genes; Genes, Fungal - genetics; genetic code; introns; lyases; Lyases - genetics; messenger RNA; Molecular Sequence Data; nucleotide sequences; nutrient availability; phylogeny; Sequence Analysis, DNA; Sequence Homology, Amino Acid; species differences; sulfur
• ISSN: 0172-8083; 1432-0983
• DOI: 10.1007/s002940050463

The metG gene of Aspergillus nidulans encoding cystathionine beta-lyase, an enzyme of the main pathway of methionine synthesis, was cloned by complementation of a metG mutation. A comparison of metG genomic DNA and a cDNA copy derived from different A. nidulans strains revealed a marked DNA sequence polymorphism manifested mostly by silent point mutations. cDNA of the A. nidulans metG gene complemented the Escherichia coli metC69 mutation impairing cystathionine beta-lyase. This gene contains two introns and codes for a protein of 439 amino acids. The protein shows homology with bacterial, yeast and plant cystathionine beta-lyases, as well as with other enzymes belonging to a large family of pyridoxal 5'-phosphate binding proteins. Transcription of the metG gene is not appreciably regulated by the concentration of sulphur source in the growth medium.