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Biochim Biophys Acta Gen Subj. 2017 Nov;1861(11 Pt A):2739-2749. doi: 10.1016/j.bbagen.2017.07.018. Epub 2017 Jul 27.

Biophysical characterization of the association of histones with single-stranded DNA.

Author information

1
Experimental Biophysics and Applied Nanoscience, Faculty of Physics, Bielefeld University, Bielefeld 33615, Germany.
2
Nanomalaria Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain; Barcelona Institute for Global Health (ISGlobal), Barcelona Center for International Health Research (CRESIB, Hospital Clínic-Universitat de Barcelona), Rosselló 149-153, Barcelona 08036, Spain; Nanoscience and Nanotechnology Institute (IN2UB), University of Barcelona, Martí i Franquès 1, Barcelona 08028, Spain. Electronic address: xfernandez_busquets@ub.edu.

Abstract

BACKGROUND:

Despite the profound current knowledge of the architecture and dynamics of nucleosomes, little is known about the structures generated by the interaction of histones with single-stranded DNA (ssDNA), which is widely present during replication and transcription.

METHODS:

Non-denaturing gel electrophoresis, transmission electron microscopy, atomic force microscopy, magnetic tweezers.

RESULTS:

Histones have a high affinity for ssDNA in 0.15M NaCl ionic strength, with an apparent binding constant similar to that calculated for their association with double-stranded DNA (dsDNA). The length of DNA (number of nucleotides in ssDNA or base pairs in dsDNA) associated with a fixed core histone mass is the same for both ssDNA and dsDNA. Although histone-ssDNA complexes show a high tendency to aggregate, nucleosome-like structures are formed at physiological salt concentrations. Core histones are able to protect ssDNA from digestion by micrococcal nuclease, and a shortening of ssDNA occurs upon its interaction with histones. The purified (+) strand of a cloned DNA fragment of nucleosomal origin has a higher affinity for histones than the purified complementary (-) strand.

CONCLUSIONS:

At physiological ionic strength histones have high affinity for ssDNA, possibly associating with it into nucleosome-like structures.

GENERAL SIGNIFICANCE:

In the cell nucleus histones may spontaneously interact with ssDNA to facilitate their participation in the replication and transcription of chromatin.

KEYWORDS:

Electrophoresis; Force spectroscopy; Histones; Magnetic tweezers; Nucleosome; Single-stranded DNA

PMID:
28756274
DOI:
10.1016/j.bbagen.2017.07.018
[Indexed for MEDLINE]

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