Title: An internal rearrangement in an Arabidopsis inverted repeat locus impairs DNA methylation triggered by the locus.

Authors: Melquist, Stacey; Bender, Judith

Published In Genetics, (2004 Jan)

Abstract: In plants, transcribed inverted repeats trigger RNA interference (RNAi) and DNA methylation of identical sequences. RNAi is caused by processing of the double-stranded RNA (dsRNA) transcript into small RNAs that promote degradation of complementary RNA sequences. However, the signals for DNA methylation remain to be fully elucidated. The Arabidopsis tryptophan biosynthetic PAI genes provide an endogenous inverted repeat that triggers DNA methylation of PAI-identical sequences. In the Wassilewskija strain, two PAI genes are arranged as a tail-to-tail inverted repeat and transcribed from an unmethylated upstream promoter. This locus directs its own methylation, as well as methylation of two unlinked singlet PAI genes. Previously, we showed that the locus is likely to make an RNA signal for methylation because suppressed transcription of the inverted repeat leads to reduced PAI methylation. Here we characterize a central rearrangement in the inverted repeat that also confers reduced PAI methylation. The rearrangement creates a premature polyadenylation signal and suppresses readthrough transcription into palindromic PAI sequences. Thus, a likely explanation for the methylation defect of the mutant locus is a failure to produce readthrough dsRNA methylation triggers.

PubMed ID: 15020434

MeSH Terms: No MeSH terms associated with this publication