Newly identified genes involved in the signal transduction of Escherichia coli K-12.

We cloned and sequenced two Escherichia coli genes which are members of a family of an environmentally responsive two-component system. The nucleotide (nt) and deduced amino-acid sequences of these two genes were found to be homologous to those of the Bordetella pertussis bvgA and bvgS genes. They were mapped at 51 min (clones 6B9 to 7G9 of the Kohara miniset library of the E. coli chromosome). Both proteins, deduced from their nt sequences, were identified in the coupled in vitro transcription-translation system; their molecular masses were consistent with BvgA and BvgS (23 and 135 kDa, respectively). Furthermore, when these genes were expressed on a multicopy plasmid in an envZ deletion strain, ompC expression was induced. This expression was found to be regulated by low temperature, MgSO4 and nicotinic acid, factors known to control the virulence of B. pertussis via BvgA and BvgS. These results indicate that the newly cloned genes were structurally and functionally similar to bvgA and bvgS, and we designated these genes evgA and evgS.