Analysis of non-coding RNAs in Methylorubrum extorquens reveals a novel small RNA specific to Methylobacteriaceae

Methylorubrum extorquens metabolizes methanol, a cheap raw material that can be derived from waste. It is a facultative methylotroph, making it a model organism to study the metabolism of one carbon compounds. Despite a considerable interest to exploit this bacteria as a biotechnological tool in a methanol-based bioeconomy, little is known about its non-coding sRNA. Small RNAs play well-documented essential roles in Escherichia coli for post-transcriptional regulation; and have important functions in many bacteria, including other Alphaproteobacteria like Agrobacterium tumefaciens. M. extorquens is expected to contain many sRNAs, especially since it also encodes for the protein Hfq, a chaperone protein important in the interaction between sRNAs and their target, but also critical for the stabilization of sRNAs themselves. Few sRNAs are annotated in the genome of this Alphaproteobacteria and they were never validated. In this study, formerly annotated sRNAs ffh, CC2171, BjrC1505 were confirmed by Northern blot, validating the expression of sRNAs in M. extorquens. Moreover, analysis of RNA-sequencing data established a considerable list of potential sRNAs. Interesting candidates selected after bioinformatic analysis were tested by Northern blot, revealing a novel sRNA specific to Methylobacteriaceae, sRNA Met2624. Its expression patterns and genomic context were analyzed. This research is the first experimental validation of sRNAs in M. extorquens and paves the way for other sRNA discoveries.