Open AccessEvolutionary divergence of the Citrobacter freundii tryptophan operon regulatory region: comparison with other enteric bacteria
Author(s) -
Miroslav Blumenberg,
Charles Yanofsky
Publication year - 1982
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.152.1.57-62.1982
Subject(s) - citrobacter freundii , operon , biology , trp operon , escherichia coli , citrobacter , repressor , salmonella , enterobacteriaceae , genetics , lac operon , peptide sequence , microbiology and biotechnology , bacteria , gene , gene expression
The regulatory region of the trp operon of Citrobacter freundii was sequenced and compared with the corresponding regions of other enteric bacteria. Significant differences were noted in the promoter region. These differences are presumably responsible for the weak expression of the cloned trp operon in Escherichia coli. The presumed operator region, although nonfunctional in E. coli, has dyad symmetry, but the sequence of the symmetrical region differs appreciably from those of operators that can be regulated by the E. coli trp repressor. The sequence of the trp leader region of C. freundii resembles that of other enteric bacteria, suggesting that the C. freundii operon is also regulated by attenuation. Comparison of the sequence of the initial portion of trpE with the homologous regions of E. coli and Salmonella typhimurium indicates that the three organisms probably are evolutionary equidistant.