Small RNAs in Bacterial Virulence and Communication

Many pathogenic bacteria transit between free-living lifestyles and the markedly different environments presented by their hosts. This requires detection, integration, and response to different external and intracellular conditions and subsequent realignment of physiology and metabolism, as well as virulence factor expression via coordinated gene expression changes. Signals detected by pathogens include not only changes in temperature, pH, or nutrient availability, but also cues from the host and neighboring bacteria. How virulence genes are regulated at the transcriptional level has been studied extensively, and the regulons of several master regulators of virulence and survival gene transcription have been described in detail ( 1 , 2 ). This has provided insight into both general regulatory mechanisms used by bacteria, and the lifestyles of pathogenic species.