Metal A and Metal B Sites of Nuclear RNA Polymerases Pol IV and Pol V Are Required for siRNA-Dependent DNA Methylation and Gene Silencing
Author Information
Author(s): Jeremy R. Haag, Olga Pontes, Craig S. Pikaard
Primary Institution: Department of Biology, Washington University, St. Louis, Missouri, United States of America
Hypothesis
If RNA Polymerases IV and V function as RNA polymerases, their Metal A and Metal B consensus sequences should be essential for their known biological activities.
Conclusion
The Metal A and Metal B sites are required for the biological functions of Pol IV and Pol V, including siRNA production, RNA-directed DNA methylation, and transposon silencing.
Supporting Evidence
- The Metal A and Metal B sites are essential for siRNA production.
- Mutations in these sites lead to loss of DNA methylation and gene silencing.
- Pol IV and Pol V are shown to be catalytically active in vivo.
Takeaway
The study found that specific parts of two plant enzymes are necessary for making small RNA molecules that help silence genes and control DNA methylation.
Methodology
Site-directed mutagenesis was used to alter the Metal A and Metal B motifs in the polymerase subunits, which were then tested in transgenic plants for restoration of function.
Limitations
The study does not address the potential for other factors influencing the observed biological functions beyond the Metal A and B sites.
Statistical Information
P-Value
p<0.05
Statistical Significance
p<0.05
Digital Object Identifier (DOI)
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