Project description:Nonsense mediated mRNA decay (NMD) is a translation-dependent surveillance pathway that eliminates RNAs with short open reading frames (ORFs) and long 3' untranslated regions (UTRs). Upf1 is the key protein of this degradation pathway and we were interested to purify the associated RNAs. Moreover we have done purifications of two proteins from the general mRNA turnover in yeast : Pab1 and Lsm1 that both bind RNAs poly(A) tails. We have also done a purification with a protein from the small ribosomal subunit (40S) in order to have a look at the translated RNAs.
Project description:Encoded model contains complete kinetics of infection for coxsackievirus B3 (CVB3), a compact and fast-acting RNA virus. The model consists of separable, detailed modules describing viral binding-delivery, translation-replication, and encapsidation. Specific module activities are dampened by the type I interferon response to viral double-stranded RNAs (dsRNAs), which is itself disrupted by viral proteinases
Project description:Adenovirus is a common human pathogen that relies on host cell processes for transcription and processing of viral RNA and protein production. Although adenoviral promoters, splice junctions, and cleavage and polyadenylation sites have been characterized using low-throughput biochemical techniques or short read cDNA-based sequencing, these technologies do not fully capture the complexity of the adenoviral transcriptome. By combining Illumina short-read and nanopore long-read direct RNA sequencing approaches, we mapped transcription start sites and cleavage and polyadenylation sites across the adenovirus genome. In addition to confirming the known canonical viral early and late RNA cassettes, our analysis of splice junctions within long RNA reads revealed an additional 35 novel viral transcripts. These RNAs include fourteen new splice junctions which lead to expression of canonical open reading frames (ORF), six novel ORF-containing transcripts, and fifteen transcripts encoding for messages that potentially alter protein functions through truncations or fusion of canonical ORFs. In addition, we also detect RNAs that bypass canonical cleavage sites and generate potential chimeric proteins by linking separate gene transcription units. Of these, an evolutionary conserved protein was detected containing the N-terminus of E4orf6 fused to the downstream DBP/E2A ORF. Loss of this novel protein, E4orf6/DBP, was associated with aberrant viral replication center morphology and poor viral spread. Our work highlights how long-read sequencing technologies can reveal further complexity within viral transcriptomes.
Project description:This experiment was to have a look at the transcriptional profiles from subjects with and without asthma following viral challenge, using Polyinosinic:polycytidylic acid (Poly IC) which is a synthetic analog of double-stranded RNA (dsRNA), a molecular pattern associated with viral infection.
Project description:We sequenced Endogenous short RNAs in Mucor circinelloides fungus grown in standard liquid culture. Short RNAs were profiled in wild type, Dicer-like 1 mutant (dcl1-), Dicer-like 2 mutant (dcl2-) and double Dicer mutant (dcl1-/dcl2-) strains. We identified many loci that produced less short RNAs in the dcl2- strain suggesting that DCL2 is the major protein generating short RNAs in Mucor circinelloides.
Project description:Packaging of segmented, double-stranded RNA viral genomes requires coordination of multiple viral proteins and RNA segments. For mammalian orthoreovirus (reovirus), evidence suggests either all ten or zero viral RNA segments are simultaneously packaged in a highly coordinated process hypothesized to exclude host RNA. Accordingly, reovirus generates genome-containing virions and “genomeless” top component particles. However, despite ostensibly lacking the genome, top component particles maintain a low level of infectivity. Whether reovirus particles can package host RNA is unknown. To gain insight into reovirus packaging potential and mechanisms, we employed next-generation RNA-sequencing to define the viral and host RNA content of purified reovirus virions and top component particles. Reovirus top component particles contained double-stranded viral RNA segments in similar proportions but at reduced levels compared to virions. Top component particles also were enriched for numerous host RNAs, especially short, non-polyadenylated transcripts, that differed by reovirus strain, independent of the viral polymerase. In contrast, virions were enriched for very few host RNAs. Collectively, these findings indicate that genome packaging into reovirus virions is exquisitely selective, while incorporation of host RNAs into top component particles is more promiscuous or differentially selective and may contribute to or result from inefficient viral RNA packaging.
Project description:We profiled vsiRNAs using two different high-throughput sequencing platforms and also developed a hybridisation-based array approach. The profiles obtained through the Solexa platform and by hybridisation were very similar to each other but different from the 454 profile. Both deep sequencing techniques revealed a strong bias in vsiRNAs for the positive strand of the virus and identified regions on the viral genome that produced vsiRNA in much higher abundance than other regions. The hybridisation approach also showed that the position of highly abundant vsiRNAs were the same in different plant species and in the absence of RDR6. We used the TerminatorTM 5'-Phosphate-Dependent Exonuclease to study the 5' end of vsiRNAs and showed that a perfect control duplex was not digested by the enzyme without denaturation and that the efficiency of the Terminator was strongly affected by the concentration of the substrate. We found that most vsiRNAs have 5' monophosphates, which was also confirmed by profiling short RNA libraries following either direct ligation of adapters to the 5' end of short RNAs or after replacing any potential 5' ends with monophosphates. The Terminator experiments also showed that vsiRNAs were not perfect duplexes. Using a sensor construct we also found that regions from the viral genome that were not complementary to highly abundant vsiRNAs were targeted in planta just as efficiently as regions recognised by abundant vsiRNAs. Different high-throughput sequencing techniques have different reproducible sequence bias and generate different profiles of short RNAs. The Terminator exonuclease does not process double-stranded RNA and because short RNAs can quickly re-anneal at high concentration, this assay can be misleading if the substrate is not denatured and not analysed in a dilution series. The sequence profiles and Terminator digests suggest that CymRSV siRNAs are produced from the structured positive strand rather than from perfect double-stranded RNA or by RNA-dependent RNA polymerase.
Project description:We profiled vsiRNAs using two different high-throughput sequencing platforms and also developed a hybridisation-based array approach. The profiles obtained through the Solexa platform and by hybridisation were very similar to each other but different from the 454 profile. Both deep sequencing techniques revealed a strong bias in vsiRNAs for the positive strand of the virus and identified regions on the viral genome that produced vsiRNA in much higher abundance than other regions. The hybridisation approach also showed that the position of highly abundant vsiRNAs were the same in different plant species and in the absence of RDR6. We used the TerminatorTM 5'-Phosphate-Dependent Exonuclease to study the 5' end of vsiRNAs and showed that a perfect control duplex was not digested by the enzyme without denaturation and that the efficiency of the Terminator was strongly affected by the concentration of the substrate. We found that most vsiRNAs have 5' monophosphates, which was also confirmed by profiling short RNA libraries following either direct ligation of adapters to the 5' end of short RNAs or after replacing any potential 5' ends with monophosphates. The Terminator experiments also showed that vsiRNAs were not perfect duplexes. Using a sensor construct we also found that regions from the viral genome that were not complementary to highly abundant vsiRNAs were targeted in planta just as efficiently as regions recognised by abundant vsiRNAs. Different high-throughput sequencing techniques have different reproducible sequence bias and generate different profiles of short RNAs. The Terminator exonuclease does not process double-stranded RNA and because short RNAs can quickly re-anneal at high concentration, this assay can be misleading if the substrate is not denatured and not analysed in a dilution series. The sequence profiles and Terminator digests suggest that CymRSV siRNAs are produced from the structured positive strand rather than from perfect double-stranded RNA or by RNA-dependent RNA polymerase.