Identification of a conserved N-terminal sequence involved in transmembrane signal transduction in EnvZ

To determine whether N-terminal sequences are involved in the transmembrane signaling mechanism of EnvZ, the nucleotide sequences of envZ genes from s everal enteric bacteria were determined. Comparative analysis revealed that the amino acid sequence between Pro41 and Glu53 was highly conserved. To f urther analyze the role of the conserved sequence, envZ of Escherichia coli was subjected to random PCR mutagenesis and mutant alleles that produced a high-osmolarity phenotype, in which ompF was repressed, were isolated. The mutations identified clustered within, as well as adjacent to, the Pro31-t o-Glu53 sequence. These findings suggest that the conserved Pro41-to-Glu53 sequence is involved in the signal transduction mechanism of EnvZ.