NOVEL MEMBERS OF THE 2-COMPONENT SIGNAL-TRANSDUCTION GENES IN ESCHERICHIA-COLI

A variety of adaptive response systems in prokaryotes often involve tw o families (two components) of signal transduction proteins, namely, s ensory kinases and response-regulators. To extend the list of such sen sor/regulator genes for Escherichia coli, we adopted a random screenin g method in this study. In particular, we isolated a series of recombi nant plasmids that are able phenotypically to suppress mutational lesi ons of both the envZ and phoR/creC genes, each of which encodes a well -characterized sensory-kinase. Among the recombinant plasmids thus iso lated, two clones (named pSN11 and pSN25) were subjected to characteri zation in detail. These analyses allowed us to identify the genetic lo ci specifying novel members of the sensor/regulator families. One (pSN 11) is located around 45 min on the E. coli genetic map, that contains two adjacent coding-sequences (baeS and baeR). The other (pSN25) is l ocated around 93 min of the genetic map, that also comprises two adjac ent coding-sequences (basS and basR). These two pairs of gene-products , thus newly identified, were revealed to belong to typical members of the sensor/regulator families. Furthermore, they were demonstrated to exhibit the in vitro phosphotransfer reaction in the presence of ATP, that is also a characteristic of the sensory-kinase and response-regu lator proteins.