THE MODEL OF NUCLEOSOME STRUCTURE BASED ON THE LOCAL ROTATION
OF THE NUCLEOHISTONE CHAIN, WHICH INDUCES ITS FOLDING
T.N. Priyatkina
St. Peterburg State University, Department of Biochemistry;
e-mail: tpriyatkina@mail.ru
An alternative model to the «double turn of DNA on the histone core» approach is forwarded based on the
biochemical, cytological, and crystallographic data on the structural organization of the chromatin units—nucleosomes.
The model assumes that the initial structure is a linear nucleohistone cord with a repeating symmetrical
histone sequence. The compact (core) particle (a minimal nucleosome) is forming upon a stepwise rotation
of DNA (kinks) at the centre and at two symmetrical sites into each repeating fragment stemming from the electrostatic
binding of the lysine ε-NH2-groups with the followed one by one phosphates of the sugar-phosphate
chain. As a result, we have a rhomboid structure composed of two counter-symmetrical DNA folds stabilized
by histone-histone interactions. Based on disposable data, the histone sequence along nucleosome DNA is deduced.
The following characteristics of the sequence are considered: continuity, non-overlapping, versatility,
and dyadic symmetry in dispose of two every kind histone molecules and the sequence on the whole. The model
is in agreement with a topology of nucleosome DNA, as well as the pattern of DNA-histone and histone-histone
interactions in chromatin.
Key words:
nucleosome, the histone octamer, DNA topology, DNA-histone and histone-histone interactions
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