Open AccessThe carB gene of Escherichia coli: a duplicated gene coding for the large subunit of carbamoyl-phosphate synthetase.
Author(s) -
Hiroshi Nyunoya,
Carol J. Lusty
Publication year - 1983
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.80.15.4629
Subject(s) - biology , nucleic acid sequence , gene , protein subunit , peptide sequence , open reading frame , escherichia coli , biochemistry , homology (biology) , coding region , microbiology and biotechnology , gene product , amino acid , genetics , scn3a , g alpha subunit , gene expression
Previous genetic and biochemical studies indicate that the carB gene of Escherichia coli codes for the large subunit of carbamoyl-phosphate synthetase (EC 6.3.5.5). We have determined the nucleotide sequence of a 4-kilobase-pair cloned fragment of E. coli DNA with genetic determinants for carB. The DNA sequence is a 3,219-nucleotide-long reading frame. The polypeptide encoded by this reading frame has been verified to be the large subunit of carbamoyl-phosphate synthetase. The gene product is similar to the large subunit in its molecular weight, amino acid composition and amino-terminal residue, and carboxyl-terminal sequence. The amino acid sequence derived from the nucleotide sequence shows a highly significant homology between the amino- and carboxyl-terminal halves of the protein. We propose that the carB gene was formed by an internal duplication of a smaller ancestral gene.