Dosage Dependent Suppression of a crp - Mutant by yciM Gene Product in Escherichia coli

Abstract

yciM, one of the uncharacterized ORFs in Escherichia coli, located next to the DNA replication terminus terA, was found to suppress a suppressor sensitive crp- mutant in 2 copies, one placed in trans in a single copy plasmid and the other on the chromosome in cis, but not in single copy on the chromosome. Moreover, it seems to be lethal to the host in multiple copies, because it could not be subcloned in a multicopy vector. The suppression sensitive crp mutation was leaky and had been credted by the insertion of an 152 element between the crp promoter and its coding region.