Whole genome mapping of 5' RNA ends in bacteria by tagged sequencing : A comprehensive view in Enterococcus faecalis

Enterococcus faecalis is the third cause of nosocomial infections. To obtain the first comprehensive view of transcriptional organizations in this bacterium, we used a modified RNA-seq approach enabling to discriminate primary from processed 5'RNA ends. We also validated our approach by confirming known features in Escherichia coli. We mapped 559 transcription start sites and 352 processing sites in E. faecalis. A blind motif search retrieved canonical features of SigA- and SigN-dependent promoters preceding TSSs mapped. We discovered 95 novel putative regulatory RNAs, small- and antisense RNAs, and 72 transcriptional antisense organisations. Presented data constitute a significant insight into bacterial RNA landscapes and a step towards the inference of regulatory processes at transcriptional and post-transcriptional levels in a comprehensive manner

A simple and efficient method to search for selected primary transcripts: non-coding and antisense RNAs in the human pathogen Enterococcus faecalis

Enterococcus faecalis is a commensal bacterium and a major opportunistic human pathogen. In this study, we combined in silico predictions with a novel 5′RACE-derivative method coined ‘5′tagRACE’, to perform the first search for non-coding RNAs (ncRNAs) encoded on the E. faecalis chromosome. We used the 5′tagRACE to simultaneously probe and characterize primary transcripts, and demonstrate here the simplicity, the reliability and the sensitivity of the method. The 5′tagRACE is complementary to tiling arrays or RNA-sequencing methods, and is also directly applicable to deep RNA sequencing and should significantly improve functional studies of bacterial RNA landscapes. From 45 selected loci of the E. faecalis chromosome, we discovered and mapped 29 novel ncRNAs, 10 putative novel mRNAs and 16 antisense transcriptional organizations. We describe in more detail the oxygen-dependent expression of one ncRNA located in an E. faecalis pathogenicity island, the existence of an ncRNA that is antisense to the ncRNA modulator of the RNA polymerase, SsrS and provide evidences for the functional interplay between two distinct toxin–antitoxin modules

Identification of new noncoding RNAs in Listeria monocytogenes and prediction of mRNA targets

To identify noncoding RNAs (ncRNAs) in the pathogenic bacterium Listeria monocytogenes, we analyzed the intergenic regions (IGRs) of strain EGD-e by in silico-based approaches. Among the twelve ncRNAs found, nine are novel and specific to the Listeria genus, and two of these ncRNAs are expressed in a growth-dependent manner. Three of the ncRNAs are transcribed in opposite direction to overlapping open reading frames (ORFs), suggesting that they act as antisense on the corresponding mRNAs. The other ncRNA genes appear as single transcription units. One of them displays five repeats of 29 nucleotides. Five of these new ncRNAs are absent from the non-pathogenic species L. innocua, raising the possibility that they might be involved in virulence. To predict mRNA targets of the ncRNAs, we developed a computational method based on thermodynamic pairing energies and known ncRNA–mRNA hybrids. Three ncRNAs, including one of the putative antisense ncRNAs, were predicted to have more than one mRNA targets. Several of them were shown to bind efficiently to the ncRNAs suggesting that our in silico approach could be used as a general tool to search for mRNA targets of ncRNAs

Fresh layers of RNA-mediated regulation in Gram-positive bacteria

International audienceBacterial regulatory RNAs have been defined as diverse classes of cis and trans elements that may intervene at each step of gene expression, from RNA and protein synthesis to degradation. Here, we report on a few examples from Gram-positive bacteria that extend the definition of regulatory RNAs to include 5' and 3' UTRs that also act as cis and trans regulators. New examples unveil the existence of cis and trans acting regulatory RNAs on a single molecule. Also, we highlight data showing that a key RNA chaperone in Enterobacteriaceae, Hfq, does not fulfill the same role in Gram-positive Firmicutes

Detection and quantitative estimation of spurious double stranded DNA formation during reverse transcription in bateria using tagRNA-seq

Standard RNA-seq has a well know tendency to generate "ghost" antisense reads due to formation of spurious second strand cDNA in the sequencing process. We recently reported on a novel variant of RNA-seq coined "tagRNA-seq" introduced for the purpose of distinguishing primary from processed transcripts in bacteria. Incidentally, the additional information provided by the tag is also very suitable for detection of true anti-sense RNA transcripts and quantification of spurious antisense signals in a sample. We briefly explain how to perform such a detection and illustrate on previously published datasets.QC 20150811</p

Régulation de l expression du Locus d effacement des entérocytes chez les escherichia coli Enterohémorragiques (rôle des ARN non-codants)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

RNA- mediated control of bacterial gene expression: rol of regulatory non-coding RNAs

Editor: Dr. Robert A. MeyersPeer Reviewe

RNA-mediated Control of Bacterial Gene Expression: Role of Regulatory non-Coding RNAs

Regulatory noncoding RNAs are found in 5′ untranslated regions of messengers RNAs, or as individual molecules transcribed from the complementary DNA strand to annotated genes (antisense RNAs) or from empty chromosomal regions (noncoding RNAs). They can regulate each step of gene expression by directly acting on transcription or translation processes via alternative folding, base-pairing to RNA targets, or binding to regulatory proteins