MAT2 in the nucleus

It seems that SAMe synthesis for DNA methylation might be happening right in the nucleus and right in place on the gene that should be methylated.

This paper describes how MAT2A partners with MafK to repress genes.

If that’s the case then we need to rethink the protocols related to SAMe and maybe shift the focus from B12 to methionine, potassium and magnesium a bit.

Proteomics analysis of MafK revealed its interaction with MATIIα, a MAT isozyme. MATIIα was localized in nuclei and found to form a dense network with chromatin-related proteins including Swi/Snf and NuRD complexes.

MATIIα was recruited to Maf recognition element (MARE) at HO-1 gene. When MATIIα was knocked down in murine hepatoma cell line, expression of HO-1 was derepressed at both basal and induced levels.

The catalytic activity of MATIIα, as well as its interacting factors such as MATIIβ, BAF53a, CHD4, and PARP1, was required for HO-1 repression.

MATII serves as a transcriptional corepressor of MafK by interacting with chromatin regulators and supplying SAM for methyltransferases. (R1)