Location of a new gene, greA, on the Escherichia coli chromosome

We have recently identified a new gene of Escherichia coli, called greA, which is involved in the regulation of cell growth at high temperature (11). The greA gene was cloned on the basis of its ability to suppress the conditional-lethal phenotype of a pleiotropic mutation in rpoB, the gene that encodes the beta subunit ofRNA polymerase (12). The rpoB mutation, ts8, was selected for its ability to confer rifampin resistance (12). It reduces cell growth at low temperature and prevents cell growth at high temperature. In addition, the ts8 mutation is an allele-specific suppressor of nusAl (4), restoring antitermination by the N gene product of phage A (12). It also suppresses the rho-15 mutation (3) in an allele-specific manner, restoring termination within the IS2 DNA insertion element (12). We have shown that all of these phenotypes of the ts8 mutation are due to a single amino acid