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PMID:16998468

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Citation

Qi, Y, He, X, Wang, XJ, Kohany, O, Jurka, J and Hannon, GJ (2006) Distinct catalytic and non-catalytic roles of ARGONAUTE4 in RNA-directed DNA methylation. Nature 443:1008-12

Abstract

DNA methylation has important functions in stable, transcriptional gene silencing, immobilization of transposable elements and genome organization. In Arabidopsis, DNA methylation can be induced by double-stranded RNA through the RNA interference (RNAi) pathway, a response known as RNA-directed DNA methylation. This requires a specialized set of RNAi components, including ARGONAUTE4 (AGO4). Here we show that AGO4 binds to small RNAs including small interfering RNAs (siRNAs) originating from transposable and repetitive elements, and cleaves target RNA transcripts. Single mutations in the Asp-Asp-His catalytic motif of AGO4 do not affect siRNA-binding activity but abolish its catalytic potential. siRNA accumulation and non-CpG DNA methylation at some loci require the catalytic activity of AGO4, whereas others are less dependent on this activity. Our results are consistent with a model in which AGO4 can function at target loci through two distinct and separable mechanisms. First, AGO4 can recruit components that signal DNA methylation in a manner independent of its catalytic activity. Second, AGO4 catalytic activity can be crucial for the generation of secondary siRNAs that reinforce its repressive effects.

Links

PubMed Online version:10.1038/nature05198

Keywords

Amino Acid Sequence; Arabidopsis Proteins/chemistry; Arabidopsis Proteins/genetics; Arabidopsis Proteins/metabolism; Argonaute Proteins; Catalysis; CpG Islands/genetics; DNA Methylation; DNA, Plant/genetics; DNA, Plant/metabolism; Humans; Molecular Sequence Data; RNA Interference; RNA, Plant/genetics; RNA, Plant/metabolism; RNA, Small Interfering/genetics; RNA, Small Interfering/metabolism; Sequence Alignment

Significance

Annotations

Gene product Qualifier GO Term Evidence Code with/from Aspect Extension Notes Status

ARATH:AGO4

enables

GO:0035198: miRNA binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

ARATH:AGO4

involved_in

GO:0080188: gene silencing by RNA-directed DNA methylation

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:AGO4

enables

GO:0035197: siRNA binding

ECO:0000315: mutant phenotype evidence used in manual assertion

F

Seeded From UniProt

complete

ARATH:AGO4

enables

GO:0004521: endoribonuclease activity

ECO:0000315: mutant phenotype evidence used in manual assertion

F

Seeded From UniProt

complete

ARATH:AGO4

involved_in

GO:0030422: siRNA processing

ECO:0000315: mutant phenotype evidence used in manual assertion

P

Seeded From UniProt

complete

ARATH:AGO1

enables

GO:0035198: miRNA binding

ECO:0000314: direct assay evidence used in manual assertion

F

Seeded From UniProt

complete

Notes

See also

References

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