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Delayed methylation and the matrix bound DNA methylase
Biochemical and Biophysical Research Communications
|January 31, 1985
Abstract:
It is shown that the methylation of DNA that occurs in isolated nuclei is "delayed methylation". This methylation is not reduced in nuclei which have been pretreated with 0.2M NaCl to extract the soluble methylase suggesting that this methylation is the product of a firmly bound matrix associated DNA methylase. Evidence is provided that, like the methylase, the DNA substrate is associated with the nuclear matrix.
Insights
DNA methylation in isolated nuclei, termed "delayed methylation", is resistant to soluble methylase extraction. This suggests a firmly bound matrix-associated DNA methylase is responsible for this epigenetic modification.
Area of Science:
- Molecular Biology
- Epigenetics
- Cell Biology
Background:
- DNA methylation is a crucial epigenetic mechanism regulating gene expression.
- Understanding the localization and activity of DNA methyltransferases (DNMTs) is key to deciphering epigenetic regulation.
- Nuclear matrix association plays a role in organizing genomic functions.
Purpose of the Study:
- To investigate the nature and localization of DNA methylase activity in isolated nuclei.
- To determine if DNA methylation observed in isolated nuclei involves soluble or matrix-associated enzymes.
- To explore the association of DNA and methylase with the nuclear matrix.
Main Methods:
- Isolation of nuclei from cellular material.
- Extraction of soluble proteins using 0.2M NaCl.
- Assessing DNA methylase activity in pretreated and untreated nuclei.
- Investigating the association of DNA methylase and DNA substrate with the nuclear matrix.
Main Results:
- A significant "delayed methylation" activity was observed in isolated nuclei.
- Pretreatment with 0.2M NaCl to remove soluble methylase did not reduce this delayed methylation.
- Evidence suggests both the DNA methylase and the DNA substrate are associated with the nuclear matrix.
Conclusions:
- The observed DNA methylation in isolated nuclei is mediated by a DNA methylase tightly bound to the nuclear matrix.
- This matrix-associated DNA methylase activity is distinct from soluble methylase activity.
- Both the enzyme and its DNA substrate are localized to the nuclear matrix, indicating a functional association within this nuclear compartment.