Fig. 8: Tentative model of siRNA production via the action of nuclear CHR11 and SGS3.
From: Arabidopsis SGS3 is recruited to chromatin by CHR11 to select RNA that initiate siRNA production
In the nucleus, SGS3 is recruited at CHR11-binding loci. When the genomic arrangement allows the production of sense and antisense RNAs forming dsRNA with a 5’ overhang, SGS3 binds to the dsRNA structure, which probably releases the CHR11-SGS3 interaction, allowing its export to the cytosol. In the cytosol, RNAs bound to SGS3 are converted to dsRNA by RDR6, followed by processing by DCL4 and DCL2 into 21-nt siRNAs that can execute PTGS and 22-nt siRNAs that allow PTGS amplification. The model described for the p35S-GUS transgene locus likely applies for endogenous PCG/NAT pairs. (This figure was entirely created by authors using ppt).
