[Structural-functional analysis of the promoter region of Escherichia coli udp gene].

Effect of mutations in the -10 and -35 regions of the udp gene promoter on the nature of its regulation by CytR and CRP proteins was studied. In studies of expression of mutant promoters, competition between RNA polymerase and the CytR repressor for the promoter region of the udp gene was shown. In the presence of the improved -10 region, the introduction of a substitution 15C-->T (that is the presence of the elongated Pribnow block) resulted in the CRP-independent transcription of the udp gene promoter.

Comparison of the structure and regulation of the udp gene of Vibrio cholerae, Yersinia pseudotuberculosis, Salmonella typhimurium, and Escherichia coli.

The nucleotide sequences of the udp gene encoding uridine phosphorylase of Yersinia pseudotuberculosis and Vibrio cholerae are presented and compared with the udp sequences of Salmonella typhimurium and Escherichia coli. Both genes contain 759 bases and encode a 253 amino acid polypeptide, which is the same as for E. coli and S.

[Determination of functional role of nucleotide composition in the transcription start region of the Escherichia coli udp gene].

The promoter of the Escherichia coli udp gene contains the poly-T (5'-TTTTT-3') motif in the transcription start region located at the distance of 3 nucleotides with respect to the Pribnow box. By means of site-directed mutagenesis, mutations in the +1, -1, and +3 positions of this region were isolated and their functional role in transcription initiation was determined. It was shown that in addition to the thymine nucleotide earlier identified at position 4 (with respect to the 5' end of the poly-T motif), the third thymine nucleotide may serve as an efficient transcription site.

[Functional interrelationship between elements of the Escherichia coli udp gene promotor responsible for binding regulatory proteins CytR, CRP, and RNA polymerase].

Site-directed mutagenesis was conducted in the regulatory region of the Escherichia coli udp gene at promoter sites responsible for binding regulatory proteins CRP and CytR as well as RNA polymerase (the core-promoter containing the--10 sequence). In mutants with an "improved"--10 region, a partial relief from the control of the cAMP-CRP transcription activation complex occurred, and the negative CytR repressor regulation was reduced. In contrast, mutant promoters with a weak Pribnow block or with a deletion that completely eliminates the core-promoter exhibited an increased ability to titrate the CytR protein in vivo.

[Protein engineering of uridine phosphorylase from Escherichia coli K-12. I. Cloning and expression of uridine phosphorylase genes from Klebsiella aerogenes and Salmonella typhimurium in E. coli].

Genes of uridine phosphorylases (udp) from Klebsiella aerogenes and Salmonella typhimurium were cloned and expressed. Highly effective producer strains of the corresponding proteins were constructed. Enzymic properties of the UPases obtained were studied and compared with those from the Escherichia coli enzyme.