Small regulatory RNA molecules in bacteria

Small non coding RNA molecules are widespread in all kingdoms of life, where they serve to regulate and fine tune gene expression. They can act in cis or trans, depending upon their structural relationship with genes whose expression they influence, and function by interacting with target messenger RNA molecules to inhibit or accelerate translation. Thus, they can exert rapid control on cellular protein levels. Within bacteria, many sRNAs have been described in Gram negative model organisms but developments in our understanding of their role in Gram positive organisms has been slower. It is clear that sRNAs influence a wide range of cellular processes, including adaptation to environmental stresses, and virulence processes in pathogens. Historically, identification of sRNAs has been challenging but recent developments in sequencing technology and computational analysis have led to over 45,000 predicted sRNAs being catalogued in the last few years. However many of these in silico predictions are yet to be validated and the complexity, in terms of sRNA interactions with gene networks, means we are really only beginning to understand how wide-ranging their effects can be within bacteria. It is clear that sRNAs play a critical role in all aspects of bacterial physiology. Within the genus Clostridium, the role of sRNAs in the pathogens C. perfringens, C. botulinum and C. difficile is much less well understood, despite hundreds of sRNAs having been predicted within these organisms. These predictions represent a platform for novel discoveries regarding post transcriptional regulatory strategies mediated by these molecules in Clostridia.