Bacterial Small RNAs (sRNAs) and Carbon Catabolite Repression

Abstract

Bacterial small RNAs (sRNAs) have been shown to play a critical role in regulation of various cellular activities by modulating the expression of key genes and operons. By using highly reliable small RNA prediction tools, the existence of sRNAs is predicted for most bacterial genomes. Bacterial strains growing in the presence of more than one carbon source show diauxie. First they grow using the more preferred substrate and then use the less preferred carbon source. There are two reasons for diauxie. One of them is that the uptake of the less preferred substrate is inhibited by the presence of the more preferred substrate by a mechanism known as inducer exclusion. The second mechanism is through catabolite repression, which is essentially transcriptional repression of genes involved in degradation of the less preferred carbon compounds. Cyclic AMP (cAMP) CRP-mediated regulation of degradative traits is known for a number of years. Recently, however, the involvement of sRNA has been demonstrated as a regulatory mechanism in carbon catabolite repression. This chapter deals primarily with bacterial sRNAs by focussing on their role in carbon catabolite repression.