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

• Published in: Biochimica et biophysica acta. General subjects Vol. 1861; no. 11; pp. 2739 - 2749
• Main Authors: Wang, Ying, van Merwyk, Luis, Tönsing, Katja, Walhorn, Volker, Anselmetti, Dario, Fernàndez-Busquets, Xavier
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.11.2017
• Subjects: atomic force microscopy; Biophysical Phenomena; Cell Nucleus - chemistry; Cell Nucleus - genetics; Chromatin - chemistry; Chromatin - genetics; digestion; DNA fragmentation; DNA Replication - genetics; DNA, Single-Stranded - chemistry; DNA, Single-Stranded - genetics; Electrophoresis; Force spectroscopy; gel electrophoresis; Histones; Histones - chemistry; Histones - genetics; ionic strength; Magnetic tweezers; magnetism; micrococcal nuclease; Nucleosome; nucleosomes; Nucleosomes - chemistry; Nucleosomes - genetics; nucleotides; Osmolar Concentration; Single-stranded DNA; sodium chloride; transmission electron microscopy; Histones; Magnetic tweezers; Electrophoresis; Single-stranded DNA; Force spectroscopy; Nucleosome
• ISSN: 0304-4165; 1872-8006
• DOI: 10.1016/j.bbagen.2017.07.018

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. Non-denaturing gel electrophoresis, transmission electron microscopy, atomic force microscopy, magnetic tweezers. 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. At physiological ionic strength histones have high affinity for ssDNA, possibly associating with it into nucleosome-like structures. In the cell nucleus histones may spontaneously interact with ssDNA to facilitate their participation in the replication and transcription of chromatin. •Histones have high affinity for single-stranded DNA at physiological ionic strength.•A fixed core histone mass complexes equal lengths of single- and double-stranded DNAs.•Histones shorten the length of single-stranded DNA in magnetic tweezers assays.•Nucleosome-like structures might be formed by histones and single-stranded DNA.