title: Influence of the rho-15 temperature-sensitive (ts) mutation on the expression of the deo-operon in Escherichia coli.
abstract: In the rho-15 temperature-sensitive (ts) mutant deo-operon enzymes show no sensitivity to catabolite repression and are not derepressed under the influence of a constitutive regulatory mutation, cytR. These data suggest that intact Rho-protein along with CRP protein is necessary for a catabolite sensitive deo-operon promoter cytP to work. In addition, there are data suggesting that Rho-factor and CRP-protein interact with each other in regulation of the deo-operon. Thus, in studies of the effect of the rho-15 (ts) and crp mutations, maximum deo-enzyme levels have been found in the double rho-15 (ts) crp mutant, and therefore intact Rho-protein in the crp genome or intact CRP-protein on the rho-15 (ts) background seems to be an obstacle for the deoP promoter in the deo-operon. In rho-15 (ts) a relative increase has been observed in the enzyme activity for a distal purine nucleoside phosphorylase gene with respect to a proximal thymidine phosphorylase gene. However in crp, the rho-15 (ts) mutation has no effect on the polarity gradient, that is on the background of impaired CRP protein Rho-factor does not seem to work as a transcription terminator within the operon.
mesh_terms: D004926:Escherichia coli / Q000235:genetics*; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D005838:Genotype; D009154:Mutation; D009876:Operon; D011683:Purine-Nucleoside Phosphorylase / Q000235:genetics; D013939:Thymidine Phosphorylase / Q000235:genetics
chemical_list: D011683:Purine-Nucleoside Phosphorylase; D013939:Thymidine Phosphorylase