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.

ABSTRACT: Plants are unique among eukaryotes in having five multi-subunit nuclear RNA polymerases: the ubiquitous RNA polymerases I, II and III plus two plant-specific activities, nuclear RNA polymerases IV and V (previously known as Polymerases IVa and IVb). Pol IV and Pol V are not required for viability but play non-redundant roles in small interfering RNA (siRNA)-mediated pathways, including a pathway that silences retrotransposons and endogenous repeats via siRNA-directed DNA methylation. RNA polymerase activity has not been demonstrated for Polymerases IV or V in vitro, making it unclear whether they are catalytically active enzymes. Their largest and second-largest subunit sequences have diverged considerably from Pol I, II and III in the vicinity of the catalytic center, yet retain the invar

SUBMITTER: Haag JR 

PROVIDER: S-EPMC2605557 | biostudies-literature | 2009

REPOSITORIES: biostudies-literature