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)

Barley stripe mosaic hordeivirus (BSMV) has a tripartite positive-sense RNA genome which encodes seven major polypeptides. Infectious in vitro transcripts derived from full-length wild-type and mutant cDNA clones have been used to investigate the contribution made by various BSMV gene products to viral RNA replication and systemic movement. We show that whereas all three of the BSMV RNA components are required for plant infection, RNAs alpha and gamma can replicate together in barley protoplasts, and therefore RNA beta must encode functions required for systemic invasion of plants. The alpha a and gamma a proteins, which contain helicase and RNA polymerase sequence motifs, together comprise the essential virus-encoded components of BSMV RNA replicase. A second BSMV protein (beta b) which contains a helicase motif is not required for RNA replication. A small cysteine-rich protein (gamma b) is dispensable for infection of plants, but in its absence the accumulation of viral coat (beta a) and beta b proteins is significantly reduced. In addition, mutations in both the gamma b and gamma a (replicase) proteins can affect the systemic movement phenotype.
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PMID:Identification of barley stripe mosaic virus genes involved in viral RNA replication and systemic movement. 220 52

Intraspecific mate selectivity often is enforced by self-incompatibility (SI), a barrier to self-pollination that inhibits productive pollen-pistil interactions. In the Brassicaceae, SI specificity is determined by two highly-polymorphic proteins: the stigmatic S-locus receptor kinase (SRK) and its pollen coat-localized ligand, the S-locus cysteine-rich protein (SCR). Arabidopsis thaliana is self fertile, but several of its accessions can be made to express SI, albeit to various degrees, by transformation with functional SRK-SCR gene pairs isolated from its close self-incompatible relative, Arabidopsis lyrata. Here, we use a newly identified induced mutation that suppresses the SI phenotype in stigmas of SRK-SCR transformants of the Col-0 accession to investigate the regulation of SI and the SRK transgene. This mutation disrupts NRPD1a, a gene that encodes a plant-specific nuclear RNA polymerase required for genomic methylation and production of some types of silencing RNAs. We show that NRPD1a, along with the RNA-dependent RNA polymerase RDR2, is required for SI in some A. thaliana accessions. We also show that Col-0 nrpd1a mutants exhibit decreased accumulation of SRK transcripts in stigmas, which is not, however, responsible for loss of SI in these plants. Together, our analysis of the nrpd1a mutation and of SRK promoter activity in various accessions reveals that the SRK transgene is subject to several levels of regulation, which vary substantially by tissue type and by accession. This study thus helps explain the well-documented differences in expression of SI exhibited by SRK-SCR transformants of different A. thaliana accessions.
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PMID:Regulation of the S-locus receptor kinase and self-incompatibility in Arabidopsis thaliana. 2339 Jun 7

In this study, we identified a novel virus from gentian (Gentiana triflora) that causes ring-spots on ovaries. Furthermore, the virus causes unusual symptoms, ring-spots that appear specifically on the outer surface of the ovarian wall after pollination. Pollen grains carrying the virus were used to infect host plants by hand-pollination. RNA extracted from purified virions indicated that the virus had two segments, RNA1 and RNA2. The full-length cDNA sequence indicated that RNA1 had two ORFs: ORF1 had methyltransferase and helicase motifs, and ORF2 had an RNA-dependent RNA polymerase motif. RNA2 had five ORFs encoding a coat protein, triple gene block proteins 1-3 and a cysteine-rich protein. The length of RNA1 was 5519 bases and that of RNA2 was 3810 bases not including a polyU/polyA region between the first and second ORFs. Viral RNA does not have a polyA tail at the 3' end. Sequence similarity and phylogenetic analysis suggested that the virus is closely related to members of the genera Pecluvirus and Hordeivirus but distinct from them. These combined results suggest that the causal agent inducing ring-spot symptoms on gentian ovaries is a new virus belonging to the family Virgaviridae but not to any presently known genus. We tentatively name the virus gentian ovary ring-spot virus.
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PMID:A novel virus transmitted through pollination causes ring-spot disease on gentian (Gentiana triflora) ovaries. 2535 17