The expanding targetome of small RNAs in Salmonella Typhimurium

The enterobacterial pathogen Salmonella has long served as a model for bacterial pathogenesis, stress response, gene expression and regulation with extensive investigation involving protein function. With the advent of high-throughput sequencing technologies and their applications in genomics and transcriptomics, a wealth of data particularly with respect to small RNAs (sRNAs) is being generated. These molecules serve as regulators of major stress response and virulence networks in diverse species including Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) and have received a lot of focus in the last decade. sRNAs are major post-transcriptional regulators that either repress or activate their targets, the former comprising the bulk of known interactions. In this review, we update and summarize validated sRNA-target regulatory information in S. Typhimurium. It covers the largest group of sRNAs in this pathogen, namely trans-encoded antisense RNAs which have received a lot of focus over the past decade. Additionally, we explore the role of Hfq as a global RNA-binding protein and highlight current techniques developed to identify sRNA targets.