A high-resolution view of RNA endonuclease cleavage in Bacillus subtilis [fiveprime_end_seq]
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ABSTRACT: RNA endonucleases are the rate-limiting initiator of decay for many bacterial mRNAs. However, the positions of cleavage and their sequence determinants remain elusive even for the well-studied Bacillus subtilis. Here we present two complementary approaches – transcriptome-wide mapping of endoribonucleolytic activity and deep mutational scanning of RNA cleavage sites – that reveal distinct rules governing the specificity among B. subtilis endoribonucleases. Detection of RNA terminal nucleotides in both 5′- and 3′-exonuclease-deficient cells revealed >103 putative endonucleolytic cleavage sites with single-nucleotide resolution. We found a surprisingly weak consensus for RNase Y targets, a contrastingly strong primary sequence motif for EndoA targets, and long-range intramolecular secondary structures for RNase III targets. Deep mutational analysis of RNase Y cleavage sites showed that the specificity is governed by many disjointed sequence features, each with mild contributions. Our results highlight the delocalized nature of mRNA stability determinants and provide a strategy for elucidating endoribonuclease specificity in vivo.
Project description:RNA endonucleases are the rate-limiting initiator of decay for many bacterial mRNAs. However, the positions of cleavage and their sequence determinants remain elusive even for the well-studied Bacillus subtilis. Here we present two complementary approaches – transcriptome-wide mapping of endoribonucleolytic activity and deep mutational scanning of RNA cleavage sites – that reveal distinct rules governing the specificity among B. subtilis endoribonucleases. Detection of RNA terminal nucleotides in both 5′- and 3′-exonuclease-deficient cells revealed >103 putative endonucleolytic cleavage sites with single-nucleotide resolution. We found a surprisingly weak consensus for RNase Y targets, a contrastingly strong primary sequence motif for EndoA targets, and long-range intramolecular secondary structures for RNase III targets. Deep mutational analysis of RNase Y cleavage sites showed that the specificity is governed by many disjointed sequence features, each with mild contributions. Our results highlight the delocalized nature of mRNA stability determinants and provide a strategy for elucidating endoribonuclease specificity in vivo.
Project description:RNA endonucleases are the rate-limiting initiator of decay for many bacterial mRNAs. However, the positions of cleavage and their sequence determinants remain elusive even for the well-studied Bacillus subtilis. Here we present two complementary approaches – transcriptome-wide mapping of endoribonucleolytic activity and deep mutational scanning of RNA cleavage sites – that reveal distinct rules governing the specificity among B. subtilis endoribonucleases. Detection of RNA terminal nucleotides in both 5′- and 3′-exonuclease-deficient cells revealed >103 putative endonucleolytic cleavage sites with single-nucleotide resolution. We found a surprisingly weak consensus for RNase Y targets, a contrastingly strong primary sequence motif for EndoA targets, and long-range intramolecular secondary structures for RNase III targets. Deep mutational analysis of RNase Y cleavage sites showed that the specificity is governed by many disjointed sequence features, each with mild contributions. Our results highlight the delocalized nature of mRNA stability determinants and provide a strategy for elucidating endoribonuclease specificity in vivo.
Project description:RNA endonucleases are the rate-limiting initiator of decay for many bacterial mRNAs. However, the positions of cleavage and their sequence determinants remain elusive even for the well-studied Bacillus subtilis. Here we present two complementary approaches – transcriptome-wide mapping of endoribonucleolytic activity and deep mutational scanning of RNA cleavage sites – that reveal distinct rules governing the specificity among B. subtilis endoribonucleases. Detection of RNA terminal nucleotides in both 5′- and 3′-exonuclease-deficient cells revealed >103 putative endonucleolytic cleavage sites with single-nucleotide resolution. We found a surprisingly weak consensus for RNase Y targets, a contrastingly strong primary sequence motif for EndoA targets, and long-range intramolecular secondary structures for RNase III targets. Deep mutational analysis of RNase Y cleavage sites showed that the specificity is governed by many disjointed sequence features, each with mild contributions. Our results highlight the delocalized nature of mRNA stability determinants and provide a strategy for elucidating endoribonuclease specificity in vivo.
Project description:RNA endonucleases are the rate-limiting initiator of decay for many bacterial mRNAs. However, the positions of cleavage and their sequence determinants remain elusive even for the well-studied Bacillus subtilis. Here we present two complementary approaches – transcriptome-wide mapping of endoribonucleolytic activity and deep mutational scanning of RNA cleavage sites – that reveal distinct rules governing the specificity among B. subtilis endoribonucleases. Detection of RNA terminal nucleotides in both 5′- and 3′-exonuclease-deficient cells revealed >103 putative endonucleolytic cleavage sites with single-nucleotide resolution. We found a surprisingly weak consensus for RNase Y targets, a contrastingly strong primary sequence motif for EndoA targets, and long-range intramolecular secondary structures for RNase III targets. Deep mutational analysis of RNase Y cleavage sites showed that the specificity is governed by many disjointed sequence features, each with mild contributions. Our results highlight the delocalized nature of mRNA stability determinants and provide a strategy for elucidating endoribonuclease specificity in vivo.
Project description:Endonucleolytic cleavage within polycistronic mRNAs can lead to differential stability and discordant abundance among co-transcribed genes. RNase Y, the major endonuclease for mRNA decay in Bacillus subtilis, was originally identified for its cleavage activity towards the cggR-gapA operon, an event that differentiates the expression of a glycolytic enzyme from its transcriptional regulator. A three-protein Y-complex (YlbF, YmcA, and YaaT) was recently identified that is also required for this cleavage in vivo, raising the possibility that it is an accessory factor acting to regulate RNase Y. However, whether the Y-complex is broadly required for RNase Y activity is unknown. Here we used end-enrichment RNA sequencing (Rend-seq) to globally identify operon mRNAs that undergo maturation post-transcriptionally by RNase Y and the Y-complex. We found that the Y-complex is required for the majority of RNase Y-mediated mRNA maturation events and affects riboswitch abundance in B. subtilis. In contrast, noncoding RNA maturation by RNase Y often do not require the Y-complex. Furthermore, deletion of RNase Y has more pleiotropic effects on the transcriptome and cell growth than deletions of the Y-complex. We propose that the Y-complex is a specificity factor for RNase Y, with evidence that its role is broadly distributed across low-GC Firmicutes.
Project description:RNA processing and degradation is initiated by endonucleolytic cleavage of the target RNAs. In many bacteria, this activity is performed by RNase E which is not present in Bacillus subtilis and other Gram-positive bacteria. Recently, the essential endoribonuclease RNase Y has been discovered in B. subtilis. This RNase is involved in the degradation of bulk mRNA suggesting a major role in mRNA metabolism. However, only a few targets of RNase Y have been identified so far. In order to assess the global impact of RNase Y, we compared the transcriptomes of strains expressing RNase Y or depleted for RNase Y. Our results indicate that processing by RNase Y results in accumulation of about 80 mRNAs. Some of these targets were substantially stabilized by RNase Y depletion, resulting in half-lives in the range of an hour. Moreover, about 40 mRNAs were less abundant when RNase Y was depleted among them the mRNAs of the operons required for biofilm formation. Interestingly, overexpression of RNase Y was sufficient to induce biofilm formation. The results emphasize the importance of RNase Y for B. subtilis and are in support of the idea that RNase Y is the functional equivalent of RNase E.
Project description:Members of the ribonuclease (RNase) III family regulate gene expression by processing double-stranded (ds) RNA. The founding member of the family, Escherichia coli (Ec) RNase III, is the most comprehensively studied and its E38A mutant (EcE38A) is an economical reagent for the preparation of small interfering (si) RNA cocktails. Previously, it was shown that EcRNase III recognizes dsRNA with little specificity and that EcE38A mainly produces 23-nucleotide (nt) siRNAs. To characterize substrate specificity and product size, we performed in vitro cleavage of dsRNAs by bacterial RNase IIIs and delineated the cleavage products by next generation sequencing. Surprisingly, we found that RNase III cleaves dsRNA at preferred sites and most siRNAs produced by EcE38A are 22 nt long. We eliminated the sequence specificity of EcE38A through the introduction of additional mutations, thereby creating a reagent that is ideally suited for producing heterogeneous siRNA cocktails to be used in gene silencing studies.
Project description:The narrow-specificity endoribonuclease RNase III and the 5’ exonuclease RNase J1 have been recently found to be not essential in the Gram-positive model organism, Bacillus subtilis. In this study, we performed a global analysis of internal 5’ ends that are generated or acted upon by these enzymes. An RNA-Seq protocol known as PARE (Parallel Analysis of RNA Ends) was used to capture 5’ monophosphorylated RNA ends in ribonuclease wild-type and mutant strains. Comparison of PARE peaks in strains with RNase III present or absent showed that, in addition to its well-known role in ribosomal (rRNA) processing, many coding sequences and intergenic regions were direct targets of RNase III. A set of regular RNA-seq experiments were performed to investigate RNA profiles in these strains and used to account for the changes in RNA abundance indirectly caused by the loss of RNase III in PARE. The PARE analysis also revealed an accumulation of 3’-proximal peaks that correlated with the absence of RNase J1, confirming the importance of RNase J1 in degrading RNA fragments that contain the transcription terminator structure. In addition, an endonuclease cleavage just two nucleotides downstream of the 16S rRNA 3’ end was discovered with PARE analysis. This latter observation begins to answer, at least for B. subtilis, a long-standing question on the exonucleolytic vs. endonucleolytic nature of 16S rRNA maturation
Project description:RNA processing and degradation is initiated by endonucleolytic cleavage of the target RNAs. In many bacteria, this activity is performed by RNase E which is not present in Bacillus subtilis and other Gram-positive bacteria. Recently, the essential endoribonuclease RNase Y has been discovered in B. subtilis. This RNase is involved in the degradation of bulk mRNA suggesting a major role in mRNA metabolism. However, only a few targets of RNase Y have been identified so far. In order to assess the global impact of RNase Y, we compared the transcriptomes of strains expressing RNase Y or depleted for RNase Y. Our results indicate that processing by RNase Y results in accumulation of about 80 mRNAs. Some of these targets were substantially stabilized by RNase Y depletion, resulting in half-lives in the range of an hour. Moreover, about 40 mRNAs were less abundant when RNase Y was depleted among them the mRNAs of the operons required for biofilm formation. Interestingly, overexpression of RNase Y was sufficient to induce biofilm formation. The results emphasize the importance of RNase Y for B. subtilis and are in support of the idea that RNase Y is the functional equivalent of RNase E. To study the global function of RNase Y, a microarray analysis was performed with a B. subtilis strain allowing controlled depletion of RNase Y. Strain GP193 (Commichau et al., 2009, Mol. Cell. Proteomics 8: 1350-1360) expressing the rny gene under the control of a xylose-inducible promoter was cultivated in CSE minimal medium in the presence or absence of the inducer xylose. The transcriptomes of the two cultures (i.e. expressing RNase Y and depleted for RNase Y) were compared at a timepoint at which the reduced RNase Y amounts already affected the mRNA turnover whereas the growth rates of the two cultures were still almost identical.
Project description:Bacteria depend on efficient RNA turnover to rapidly alter gene expression, essentially for responding to changing conditions. Nevertheless, remarkably few details are known about the rate-limiting steps in targeting and decay of RNA. The membrane-anchored endoribonuclease RNase Y is a virulence factor in Gram- positive pathogens. We have obtained a global picture of RNase Y sequence specificity using RNA-seq and the novel transcriptome-wide EMOTE method. Ninety- nine endoribonucleolytic sites produced in vivo were precisely mapped, notably inside six out of seven genes whose half-lives increase the most in an RNase Y deletion mutant, and additionally to three separate transcripts encoding degradation ribonucleases, including RNase Y itself, suggesting a regulatory network. We show that RNase Y is required to initiate the major degradation pathway of a defined sub-set of transcripts that are inaccessible to other ribonucleases, but is prevented from promiscuous activity by membrane confinement and sequence preference for guanosines. Rnase Y activity in S. aureus is analysed on a genome wide scale under two perspectives: a RNA decay timecourse with mRNA-seq; and exact position of cleavage with an EMOTE assay (Exact Mapping Of Trancripts Ends)