A possible role of chromatin and tightly-bound chromatin proteins on enzyme-catalyzed methylation of DNA.
Upon extensive digestion with DNAaseI of placenta chromatin matrix, previously "stripped" from its loosely-bound components by high-salt extraction, a fraction is obtained that contains almost no endogenous DNA methylase activity but whose DNA, if still included in this whole fraction--not if it has been purified to a protein-free condition--is a good substrate for externally added enzyme. This chromatin matrix can even cause a significant stimulation of methylation of single-stranded Micrococcus luteus DNA by placental methylase. In vivo, this phenomenon may have possible counterparts in the existence of highly-methylated regions of chromatin loops that appear to be protected by tightly-bound protein components from digestion of the "stripped loops" with DNAaseI.
Strom
R
R
Dipartimento di Biopatologia Umana, Universitá di Roma, La Sapienza, Italy.
Caiafa
P
P
Mastrantonio
S
S
Rispoli
M
M
Reale
A
A
Attinà
M
M
Cacace
F
F
D044503:5-Methylcytosine; D002843:Chromatin / Q000378:metabolism*; D003596:Cytosine / Q000031:analogs & derivatives / Q000032:analysis; D004247:DNA / Q000032:analysis / Q000378:metabolism*; D015254:DNA Modification Methylases / Q000378:metabolism*; D005260:Female; D006801:Humans; D007700:Kinetics; D008745:Methylation; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D012995:Solubility
D002843:Chromatin; D044503:5-Methylcytosine; D003596:Cytosine; D004247:DNA; D015254:DNA Modification Methylases