Nucleotide Sequence Divergence in the α -Chain-Structural Genes of Tryptophan Synthetase from Escherichia coli, Salmonella typhimurium, and Aerobacter aerogenes
Abstract
Two different estimates were obtained for the extent of nucleotide sequence divergence in the structural genes of the tryptophan synthetase α-chains of Escherichia coli, Salmonella typhimurium, and Aerobacter aerogenes. One estimate was based on comparisons of the amino acid sequences of the respective α chains. The other was derived from measurements of the thermal stability of RNA-DNA hybrids formed with phage DNA carrying the α-chain structural gene of E. coli and labeled messenger RNA from the three bacterial species. Comparison of the two estimates suggests that during the course of evolution synonymous codon changes have accumulated in the α-chain-structural genes.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- April 1973
- DOI:
- 10.1073/pnas.70.4.1112
- Bibcode:
- 1973PNAS...70.1112L