[Formation of an additional promotor in the regulatory region of the Escherichia coli udp gene and its structural and functional characterization].

Structural and functional organization of the mutant udpP18 promoter generated after the spontaneous deletion of the G base in the -79 position relative to the start site of transcription from the main (P1) promoter within the regulatory region of the udp gene was studied. In this mutant, a new, functionally active promoter (P2) with the start site of transcription in the -64 position that contained the typical motif 5'-TG-3' located in front of the Pribnow sequence was formed. The data presented suggest that the expression of the P2 promoter, unlike that of P1, is not subjected to regulation with participation of the CytR protein and the cAMP-CRP complex. Results of mutational analysis of the P2 promoter showed that substitutions of the nucleotide G in the -14 position and nucleotide T in the -15 position significantly diminish the level of transcription from the P2 promoter. On the basis of these data, it is concluded that the P2 promoter could be assigned with respect to its characteristics to a group of promoters with an extended -10 region. The synergistic effect of P1 and P2 promoters on total expression of the udp gene in the mutant udpP18 was detected.