Functional Consequences of Subunit Diversity in RNA Polymerases II and V

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Elsevier (Cell Press)
Multisubunit RNA polymerases IV and V (Pol IV and Pol V) evolved as specialized forms of Pol II that mediate RNA-directed DNA methylation (RdDM) and transcriptional silencing of transposons, viruses, and endogenous repeats in plants. Among the subunits common to Arabidopsis thaliana Pols II, IV, and V are 93% identical alternative ninth subunits, NRP(B/D/E)9a and NRP(B/D/E)9b. The 9a and 9b subunit variants are incompletely redundant with respect to Pol II; whereas double mutants are embryo lethal, single mutants are viable, yet phenotypically distinct. Likewise, 9a or 9b can associate with Pols IV or V but RNA-directed DNA methylation is impaired only in 9b mutants. Based on genetic and molecular tests, we attribute the defect in RdDM to impaired Pol V function. Collectively, our results reveal a role for the ninth subunit in RNA silencing and demonstrate that subunit diversity generates functionally distinct subtypes of RNA polymerases II and V.
RNA polymerase, RNA polymerase II, RNA polymerase V, unclassified drug, Arabidopsis, controlled study, DNA methylation, enzyme activity, gene silencing, nonhuman, nuclear RNA polymerase B9a gene, nuclear RNA polymerase B9b gene, nuclear RNA polymerase D9a gene, nuclear RNA polymerase E9a gene, nuclear RNA polymerase E9b gene, nucleotide sequence, phenotype, plant gene, structure analysis, transcription termination, transgene, Amino Acid Sequence, Arabidopsis, Arabidopsis Proteins, Crosses, Genetic, DNA Methylation, DNA, Bacterial, DNA-Directed RNA Polymerases, Gene Expression Regulation, Plant, Gene Silencing, Molecular Sequence Data, Phylogeny, Mutation, Plants, Genetically Modified, Protein Subunits, RNA Polymerase II, RNA, Messenger, Sequence Alignment, Transgenes, Arabidopsis thaliana
Tan, E. H., Blevins, T., Ream, T. S., & Pikaard, C. S. (2012). Functional consequences of subunit diversity in RNA polymerases II and V. Cell Reports, 1(3), 208-214.
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