Non-coding regulatory sRNAs from bacteria of the Burkholderia cepacia complex

Abstract

Small non-coding RNAs (sRNAs) are key regulators of post-transcriptional gene expression in bacteria. Hundreds of sRNAs have been found using in silico genome analysis and experimentally based approaches in bacteria of the Burkholderia cepacia complex (Bcc). However, and despite the hundreds of sRNAs identified so far, the number of functionally characterized sRNAs from these bacteria remains very limited. In this mini-review, we describe the general characteristics of sRNAs and the main mechanisms involved in their action as regulators of post-transcriptional gene expression, as well as the work done so far in the identification and characterization of sRNAs from Bcc. The number of functionally characterized sRNAs from Bcc is expected to increase and to add new knowledge on the biology of these bacteria, leading to novel therapeutic approaches to tackle the infections caused by these opportunistic pathogens, particularly severe among cystic fibrosis patients. KEY POINTS: •Hundreds of sRNAs have been identified in Burkholderia cepacia complex bacteria (Bcc). •A few sRNAs have been functionally characterized in Bcc. •Functionally characterized Bcc sRNAs play major roles in metabolism, biofilm formation, and virulence.

Keywords: Burkholderia cepacia complex; Post-transcriptional regulation; Small non-coding RNAs.

Fig. 1

Main mechanisms of sRNA-mRNA interaction. The interaction of sRNAs with their target mRNA can result in the repression or activation of the translation. In the case of translation repression, the sRNA binds to the mRNA Ribosome Binding Site (RBS) region, and translation is inhibited (upper panel). This interaction can lead to the restructuring of the mRNA, exposing nucleolytic sites. RNase E has been reported to be part of the complex made by the sRNA, the mRNA, and the chaperone Hfq (central panel). Activation of translation occurs when the secondary structure adopted by the mRNA does not allow its translation. When this inactive mRNA interacts with the sRNA, in a region usually close to the 5´end, the mRNA secondary structure is rearranged, the RBS becomes exposed, and translation can occur (lower panel). CDS, coding sequence. Created with BioRender.com (license number ST26KPJ2S6)

Fig. 2

Schematic representation of known sRNAs and their impact on Bcc bacteria. An * indicates a predicted function not fully demonstrated. Fe, N, C: iron, nitrogen, and carbon metabolism. ROS, reactive oxygen species. Created with BioRender.com (license number XF26KPKM64)