Self-Perpetuating Structural States in Biology, Disease, and Genetics (2002) / Chapter Skim
Currently Skimming:
Locus-specific control of asymmetric and CpNpG methylation by the DRM and CMT3 methyltransferase genes
Locus-specific control of asymmetric and CpNpG methylation by the DRM and CMT3 methyltransferase genes
Pages 115-122
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 115... ...
genes are required for de nova DNA methylation in Arabidopsis thaliana because drm1 drm2 double mutants lack the de nova methylation normally associated with transgene silencing. In this study, we have used bisulfite sequencing and Southern blot analysis to examine the role of the DRM loci in the maintenance of asymmetric methylation.
|
From page 116... ...
We found that drml drm2 double mutants lacked de novo methylation of the direct repeats of the FWA locus, which normally occurs when FWA is transformed into wild-type plants (39~. drml drm2 double mutants also blocked de novo methylation of the SUP locus, which occurs in the presence of a SUP inverted repeat.
|
From page 117... ...
However, CpG methylation levels were similar to the wild type. We used Southern blot analysis with methylation-sensitive restriction enzymes to confirm some of the bisulfite sequencing results at FWA and MEA-ISR.
|
From page 118... ...
, a transgenic allele called clk-st shows a stable nonreverting phenotype, making it more suitable for genetic studies (24~. clk-st contains a single inverted repeat of the SUP locus, which can induce de novo methylation of itself as well as of the endogenous SUP locus (described in detail in reference 39~.
|
From page 119... ...
3~. Neither the drm single mutants nor the drml drm2 double mutants affected the pattern of enzyme digestion, suggesting that the DRM genes do not play a role in maintaining CpG or CpNpG methylation at these sequences.
|
From page 120... ...
The results of this and other studies suggest that MET1 is specific for CpG methylation, and yet metl mutants show a strong reduction in non-CpG methylation at most loci examined (20, 22-25~. The strongest evidence that MET1 does not directly methylate non-CpG sites, is that all traces of non-CpG methylation are lost in drml drm2 cmt3-7 triple mutants, which contain a wild-type MET1 gene.
|
From page 121... ...
Furthermore, drml drm2 double mutants blocked de novo CpNpG and asymmetric methylation and gene silencing of the endogenous SUP locus, which normally occurs in the presence of a SUP inverted repeat transgene locus. These experiments suggest that the DRM genes encode enzymes capable of methylating previously unmodified DNA, and that CMT3 cannot substitute for this function.
|
From page 122... ...
(1994) Nucleic Acids Res.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.