Open AccessStructure of mouse DNA (cytosine‐5‐)‐methyltransferase
Author(s) -
SPIESS Eberhard,
TOMASSETTI Antonella,
HERNAIZDRIEVER Pablo,
PFEIFER Gerd P.
Publication year - 1988
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1988.tb14341.x-i2
Subject(s) - dna methyltransferase , cytosine , enzyme , dna , methyltransferase , restriction enzyme , chemistry , molecular mass , biochemistry , stereochemistry , substrate (aquarium) , transferase , microbiology and biotechnology , crystallography , biology , methylation , ecology
DNA (cytosine‐5‐)‐methyltransferase was purified as a single polypeptide (190 kDa by SDS‐PAGE) from mouse P815 mastocytoma cells. This enzyme transfers methyl groups to unmethylated as well as to hemimethylated DNA sites with a strong preference for the hemimethylated substrate. A structural analysis of the isolated enzyme by electron microscopical techniques was undertaken. On the basis of the results obtained, we propose a model for the enzyme structure. This model describes the enzyme as a hemi‐elliptical globular structure with dimensions of 5.4–6.7 nm for the height h and 10.3–10.8 nm for the diameter d , respectively; this globular structure bears a small appendix at the flat side. A molecular mass of 235–250 kDa is calculated from the measured dimensions. Limited trypsin digestion of the enzyme led to a 160‐kDa fragment which preserved the gross morphology of the original material. The possible structure function relationships are discussed.