TITLE:
A New Histone Structure Which Binds DNA at Its Eight Subunit N-Termini
AUTHORS:
Ken Biegeleisen
KEYWORDS:
Histone, Octamer, Nucleosome, Protamine, Helix
JOURNAL NAME:
Open Access Library Journal,
Vol.3 No.2,
February
29,
2016
ABSTRACT: A new model for the nucleosome is presented. The histone octamer core is
unchanged, but the location of the DNA is different. Since the highest number,
and highest concentration of positively-charged amino acid residues is located
not in the “superhelical ramp” of the octamer core, but rather in the domain of
the eight histone subunit N-termini collectively, the DNA is therefore placed
there. The role models for the protein and DNA structures in the N-terminal
domain are taken from the comparable role models for protein and DNA in the
protamine-DNA complex in sperm cells. The histone subunit N-termini are each
modeled as beta-strands, with psi/phi values of approximately /﹣130.5°
respectively, which gives a straight chain. The DNA is modeled according to the
“straight ladder” model of Tai Te Wu. Each DNA phosphate group is bound to a
lysine or arginine residue of histone by a 3 A salt bridge. The new model lends
itself so readily to further models of higher-order chromatin structure that
the problem shifts entirely, from one of deducing any higher-order structure at
all, to one of distinguishing between several models which compete for our
attention.