The gene coding for carbamoyl-phosphate synthetase I was formed by fusion of an ancestral glutaminase gene and a synthetase gene

H. Nyunoya, K. E. Broglie, C. J. Lusty

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

A near full-length cDNA copy of rat carbamoyl-phosphate synthetase I (EC 6.3.4.16) mRNA has been cloned. The cDNA insert in the recombinant plasmid pHN234 is 5.3 kilobases long. Analysis of the sequence coding for carbamoyl-phosphate synthetase I indicates that the gene has arisen from a fusion of two ancestral genes: one homologous to Escherichia coli carA, coding for a glutaminase subunit, and the second homologous to the carB gene that codes for the synthetase subunit. A short amino acid sequence previously proposed to be part of the active site involved in glutamine amide nitrogen transfer in the E. coli and yeast carbamoyl-phosphate synthetases (EC 6.3.5.5) is also present in the rat enzyme. In the mammalian enzyme, however, the glutaminase domain lacks a cysteine residue previously shown to interact with glutamine. The cysteine is replaced by a serine residue. This substitution could, in part, account for the inability of mammalian carbamoyl-phosphate synthetase I to catalyze the hydrolysis of glutamine to glutamic acid and ammonia.

Original languageEnglish
Pages (from-to)2244-2246
Number of pages3
JournalProceedings of the National Academy of Sciences of the United States of America
Volume82
Issue number8
DOIs
Publication statusPublished - 1985 Jan 1
Externally publishedYes

ASJC Scopus subject areas

  • General

Fingerprint Dive into the research topics of 'The gene coding for carbamoyl-phosphate synthetase I was formed by fusion of an ancestral glutaminase gene and a synthetase gene'. Together they form a unique fingerprint.

  • Cite this