tailieunhanh - Báo cáo khoa học: A neomorphic sgs3 allele stabilizing miRNA cleavage products reveals that SGS3 acts as a homodimer

The putative RNA-binding protein SUPPRESSOR OF GENE SILEN-CING 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. | A neomorphic sgs3 allele stabilizing miRNA cleavage products reveals that SGS3 acts as a homodimer Taline Elmayan1 Xavier Adenot1 Lionel Gissot1 2 Dominique Lauressergues1 3 Isabelle Gy1 and Herve Vaucheret1 1 Laboratoire de Biologie Cellulaire Institut Jean-Pierre Bourgin INRA Versaille France 2 Plateforme de Cytologie et d Imagerie Végétale Institut Jean-Pierre Bourgin INRA Versailles France 3 UMR 5546 CNRS Universite Toulouse III Surfaces Cellulaires et Signalisation chez les Vegetaux Castanet Tolosan France Keywords homodimer neomorphic allele RNA stabilization RNAi siRNA Correspondence T. Elmayan Laboratoire de Biologie Cellulaire Institut Jean-Pierre Bourgin INRA Institut Nationalde la Recherche Agronomique 78026 Versailles Cedex France Fax 33 01 30 83 30 99 Tel 33 01 30 83 30 29 E-mail elmayan@ Received 1 October 2008 revised 20 November 2008 accepted 3 December 2008 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 neo-morphic allele that shows increased RNA protective activity resulting in decreased RNA processing by downstream post-transcriptional gene silencing and trans-acting siRNA pathway components. doi RNA silencing was discovered in plants more .