Conserved regulatory elements of the promoter sequence of the gene rpoH ofenteric bacteria

The rpoH regulatory region of different members of the enteric bacteria fam ily was sequenced or downloaded from GenBank and compared. In addition, the transcriptional start sites of rpoH of Yersinia frederiksenii and Proteus mirabilis, two distant members of this family, were determined, Sequences s imilar to the sigma (70) promoters P1, P4 and P5, to the sigma (E) promoter P3 and to boxes DnaA1, DnaA2, cAMP receptor protein (CRP) boxes CRP1, CRP2 and box CytR present In Escherichia coli K12, were identified in sequences of closely related bacteria such as: E.coli, Shigella flexneri, Salmonella enterica serovar Typhimurium, Citrobacter freundii, Enterobacter cloacae a nd Klebsiella pneumoniae. In more distant bacteria, Y.frederiksenii and P.m irabilis, the rpoH regulatory region has a distal P1-like sigma (70) promot er and two proximal promoters: a heat-induced sigma (E)-like promoter and a sigma (70) promoter, Sequences similar to the regulatory boxes were not id entified in these bacteria, This study suggests that the general pattern of transcription of the rpoH gene in enteric bacteria includes a distal sigma (70) promoter, >200 nt upstream of the initiation codon, and two proximal promoters: a heat-induced sigma (E)-like promoter and a sigma (70) promoter , A second proximal sigma (70) promoter under catabolite-regulation is prob ably present only in bacteria closely related to E.coli.