Open AccessComplexes of the arginine-rich histone tetramer (H3)2(H4)2with negatively supercoiled DNA: electron microscopy and chemical cross-linking
Author(s) -
Jean O. Thomas,
P Oudet
Publication year - 1979
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/7.3.611
Subject(s) - tetramer , biology , dna , electron microscope , histone , nucleoprotein , nucleosome , dna supercoil , base pair , crystallography , biophysics , microbiology and biotechnology , histone octamer , biochemistry , dna replication , chemistry , enzyme , optics , physics
Tetramers of the arginine-rich histones H3 and H4 associate with supercoiled SV40 DNA either singly, giving tetrameric nucleoprotein complexes or in pairs giving octameric complexes, both of which are visualized as beads in the electron microscope. The relative amounts of the two complexes may be revealed by complete cross-linking of the proteins, followed by analysis in SDS-polyacrylamide gels. By electron microscopy of unmodified and of cross-linked complexes, both the tetrameric and the octameric complexes are shown to have a diameter of 8-9 nm and to contain about 145 base pairs (a nucleosome core length) of DNA. The compaction of the DNA in both cases is thus similar to that in the nucleosome, which has a diameter of about 12.5 nm and contains 200 base pairs of DNA.