Effects of C5 protein on transcription of the ssrA gene in escherichia coli

Abstract

10Sa RNA is one of small stable RNAs in Escherichia coli. About 1000 copies of 10Sa RNA are present per haploid cell. A 10Sa RNA precursor is processed to generate the mature form. E. coli mutants that fail to synthesize 10Sa RNA are viable with the only observable phenotypic alterations being slower growth and slow recovery from carbon starvation. Roles of 10Sa RNA is not precisely understood. It has been known that C5 protein, the protein component of RNase P, affects synthesis of M1 RNA (10Sb RNA), the RNA component of RNase P, which is also one of small stable RNAs. Since regulation of synthesis of stable RNAs is closely linked, we examined the effects of C5 protein on 10Sa RNA synthesis in E. coli. Amounts of 10Sa RNA in cells producing a high level of C5 protein upon induction with IPTG were analyzed by Northern hybridization. The ssrA gene encoding 10Sa RNA was cloned by PCR amplification from E. coli chromosomal DNA. Antisense 10Sa RNA was synthesized by in vitro transcription and used as a probe for Northern hybridization. The amount of 10Sa precursor increased and the mature 10Sa RNA decreased as the intracellular concentration of C5 protein increased upon induction with IPTG The results suggest that the overproduction of C5 protein increases transcription of 10Sa RNA and promotes the degradation of mature 10Sa RNA.