A bipartite sequence element associated with matrix/scaffold attachment regions.
We have identified a MAR/SAR recognition signature (MRS) which is common to a large group of matrix and scaffold attachment regions. The MRS is composed of two degenerate sequences (AATAAYAA and AWWRTAANNWWGNNNC) within close proximity. Analysis of >300 kb of genomic sequence from a variety of eukaryotic organisms shows that the MRS faithfully predicts 80% of MARs and SARs. In each case where we find a MRS, the corresponding DNA region binds specifically to the nuclear scaffold. Although all MRSs are associated with a SAR, not all known SARs and MARs contain a MRS, suggesting that at least two classes exist, one containing a MRS, the other not. Evidence is presented that the two sequence elements of the bipartite MRS occupy a position on the nucleosome near the dyad axis, together creating a putative protein binding site. The identification of a MAR- and SAR-associated DNA element is an important step forward towards understanding the molecular mechanisms of these elements. It will allow: (i) analysis of the genomic location of SARs, e.g. in relationship to genes, based on sequence information alone, rather than on the basis of an elaborate biochemical assay; (ii) identification and analysis of proteins that specifically bind to the MRS.