Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eriophyid mite-transmitted, multipartite, negative-sense RNA plant viruses with membrane-bound spherical virions are classified in the genus Emaravirus. We report here that the eriophyid mite-transmitted Wheat mosaic virus (WMoV), an Emaravirus, contains eight genomic RNA segments, the most in a known negative-sense RNA plant virus. Remarkably, two RNA 3 consensus sequences, encoding the nucleocapsid protein, were found with 12.5% sequence divergence, while no heterogeneity was observed in the consensus sequences of additional genomic RNA segments. The RNA-dependent RNA polymerase, glycoprotein precursor, nucleocapsid, and P4 proteins of WMoV exhibited limited sequence homology with the orthologous proteins of other emaraviruses, while proteins encoded by additional genomic RNA segments displayed no significant homology with proteins reported in GenBank, suggesting that the genus Emaravirus evolved further with a divergent octapartite genome. Phylogenetic analyses revealed that WMoV formed an evolutionary link between members of the Emaravirus genus and the family Bunyaviridae. Furthermore, genomic-length virus- and virus-complementary (vc)-sense strands of all WMoV genomic RNAs accumulated asymmetrically in infected wheat, with 10- to 20-fold more virus-sense genomic RNAs than vc-sense RNAs. These data further confirm the octapartite negative-sense polarity of the WMoV genome. In WMoV-infected wheat, subgenomic-length mRNAs of vc sense were detected for genomic RNAs 3, 4, 7, and 8 but not for other RNA species, suggesting that the open reading frames present in the complementary sense of genomic RNAs are expressed through subgenomic- or near-genomic-length vc-sense mRNAs. Importance: Wheat mosaic virus (WMoV), an Emaravirus, is the causal agent of High Plains disease of wheat and maize. In this study, we demonstrated that the genome of WMoV comprises eight negative-sense RNA segments with an unusual sequence polymorphism in an RNA encoding the nucleocapsid protein but not in the additional genomic RNA segments. WMoV proteins displayed weak or no homology with reported emaraviruses, suggesting that the genus Emaravirus further evolved with a divergent octapartite genome. The current study also examined the profile of WMoV RNA accumulation in wheat and provided evidence for the synthesis of subgenomic-length mRNAs of virus complementary sense. This is the first report to demonstrate that emaraviruses produce subgenomic-length mRNAs that are most likely utilized for genome expression. Importantly, this study facilitates the examination of gene functions and virus diversity and the development of effective diagnostic methods and management strategies for an economically important but poorly understood virus.
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PMID:An eriophyid mite-transmitted plant virus contains eight genomic RNA segments with unusual heterogeneity in the nucleocapsid protein. 2608 40

A novel mycovirus tentatively assigned the name Sclerotinia sclerotiorum hypovirus 2 (SsHV2/5472) was detected in the phytopathogenic fungus Sclerotinia sclerotiorum. The genome is 14581 nucleotides (nts) long, excluding the poly (A) tail. A papain-like cysteine protease (Pro), an RNA-dependent RNA polymerase (RdRp) and a helicase (Hel) domain were detected in the polyprotein. Phylogenetic analysis based on multiple alignments of the aa sequence of the polyprotein placed it in a distinct clade from Alphahypovirus and Betahypovirus. The distinct aa sequence plus the fact that SsHV2/5472 possesses the longest reported genome for a hypovirus, suggests that SsHV2/5472 may represent a new genus in the family Hypoviridae. Eliminating SsHV2/5472 from S. sclerotiorum significantly increased the virulence of the protoplast virus-free derivative 5472-P5, although SsHV/5472-containing isolates showed significant variation in their virulence. In addition, membrane-bound vesicles (25-50 nm) were observed in ultrathin mycelial sections of SsHV2/5472 containing isolates but not in SsHV2/5472-free isolate.
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PMID:Characterisation of a novel hypovirus from Sclerotinia sclerotiorum potentially representing a new genus within the Hypoviridae. 2510 82

Establishment of in vitro systems to study mechanisms of RNA synthesis for positive strand RNA viruses have been very useful in the past and have shed light on the composition of protein and RNA components, optimum conditions, the nature of the products formed, cis-acting RNA elements and trans-acting protein factors required for efficient synthesis. In this review, we summarize our current understanding regarding the requirements for flavivirus RNA synthesis in vitro. We describe details of reaction conditions, the specificity of template used by either the multi-component membrane-bound viral replicase complex or by purified, recombinant RNA-dependent RNA polymerase. We also discuss future perspectives to extend the boundaries of our knowledge.
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PMID:Flavivirus RNA synthesis in vitro. 2627 47

Autophagy is an evolutionarily conserved pathway in eukaryotes that delivers unwanted cytoplasmic materials to the lysosome/vacuole for degradation/recycling. Stimulated autophagy emerges as an integral part of plant immunity against intracellular pathogens. In this study, we used turnip mosaic virus (TuMV) as a model to investigate the involvement of autophagy in plant RNA virus infection. The small integral membrane protein 6K2 of TuMV, known as a marker of the virus replication site and an elicitor of the unfolded protein response (UPR), upregulates the selective autophagy receptor gene NBR1 in a UPR-dependent manner. NBR1 interacts with TuMV NIb, the RNA-dependent RNA polymerase of the virus replication complex (VRC), and the autophagy cargo receptor/adaptor protein ATG8f. The NIb/NBR1/ATG8f interaction complexes colocalise with the 6K2-stained VRC. Overexpression of NBR1 or ATG8f enhances TuMV replication, and deficiency of NBR1 or ATG8f inhibits virus infection. In addition, ATG8f interacts with the tonoplast-specific protein TIP1 and the NBR1/ATG8f-containing VRC is enclosed by the TIP1-labelled tonoplast. In TuMV-infected cells, numerous membrane-bound viral particles are evident in the vacuole. Altogether these results suggest that TuMV activates and manipulates UPR-dependent NBR1-ATG8f autophagy to target the VRC to the tonoplast to promote viral replication and virion accumulation.
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PMID:A plant RNA virus activates selective autophagy in a UPR-dependent manner to promote virus infection. 3247 43

Single-stranded, positive-sense RNA viruses encode essential replication polyproteins which are composed of several domains. They are usually subjected to finely regulated proteolytic maturation processes to generate cleavage intermediates and end-products. Both polyproteins and maturation products play multiple key roles that ultimately allow synthesis of viral genome progeny. Despite the importance of these proteins in the course of viral replication, their structural properties, including the conformational changes regulating their numerous functions, are poorly described at the structural level. This lack of information is mainly due to the extreme difficulty to express large, membrane-bound, multi-domain proteins with criteria suitable for structural biology methods. To tackle this challenge, we have used a wheat-germ cell-free expression system. We firstly establish that this approach allows to synthesize viral polyproteins encoded by two unrelated positive-sense RNA viruses, a human norovirus and a plant tymovirus. Then, we demonstrate that these polyproteins are fully functional and are spontaneously auto-cleaved by their active protease domain, giving rise to natural maturation products. Moreover, we show that introduction of point mutations in polyproteins allows to inhibit the proteolytic maturation process of each virus. This allowed us to express and partially purify the uncleaved full-length norovirus polyprotein and the tymoviral RNA-dependent RNA polymerase. Thus, this study provides a powerful tool to obtain soluble viral polyproteins and their maturation products in order to conduct challenging structural biology projects and therefore solve unanswered questions.
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PMID:In vitro translation of virally-encoded replication polyproteins to recapitulate polyprotein maturation processes. 3268 58


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