A neomorphic sgs3 allele stabilizing miRNA cleavage products reveals that SGS3 acts as a homodimer.
The putative RNA-binding protein SUPPRESSOR OF GENE SILENCING 3 (SGS3) protects RNA from degradation before transformation into dsRNA by the RNA-dependent RNA polymerase RDR6 during plant post-transcriptional gene silencing and trans-acting small interfering (siRNA) pathways. In this study, we show that SGS3 acts as a homodimer, and that the point mutation sgs3-3 impairs post-transcriptional gene silencing in a dominant-negative manner through the formation of SGS3/sgs3-3 heterodimers. Unlike complete-loss-of-function sgs3 mutants, which are impaired in the accumulation of both micro RNA-directed TAS cleavage products and mature trans-acting siRNAs, the sgs3-3 mutant overaccumulates TAS cleavage products and exhibits slightly reduced trans-acting siRNA accumulation. Together, these results suggest that sgs3-3 is a neomorphic allele that shows increased RNA protective activity, resulting in decreased RNA processing by downstream post-transcriptional gene silencing and trans-acting siRNA pathway components.
Elmayan
Taline
T
Laboratoire de Biologie Cellulaire, Institut Jean-Pierre Bourgin, INRA, Versaille, France. elmayan@versailles.inra.fr
Adenot
Xavier
X
Gissot
Lionel
L
Lauressergues
Dominique
D
Gy
Isabelle
I
Vaucheret
Hervé
H
D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D051545:Cyclooxygenase 1 / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D055503:Protein Multimerization; D020798:Two-Hybrid System Techniques
D029681:Arabidopsis Proteins; D035683:MicroRNAs; C410507:SGS3 protein, Arabidopsis; D051545:Cyclooxygenase 1