Nucleotide excision repair (NER) is a major DNA repair mechanism that recognizes a broad range of DNA damages. In Escherichia coli, damage recognition in NER is accomplished by the UvrA and UvrB proteins. We have analysed the structural properties of the different protein-DNA complexes formed by UvrA, UvrB and (damaged) DNA using atomic force microscopy. Analysis of the UvrA(2)B complex in search of damage revealed the DNA to be wrapped around the UvrB protein, comprising a region of about seven helical turns. In the UvrB-DNA pre-incision complex the DNA is wrapped in a similar way and this DNA configuration is dependent on ATP binding. Based on these results, a role for DNA wrapping in damage recognition is proposed. Evidence is presented that DNA wrapping in the pre-incision complex also stimulates the rate of incision by UvrC.
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http://dx.doi.org/10.1093/emboj/20.3.601 | DOI Listing |
Int J Mol Sci
December 2024
Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA.
In eukaryotic nuclei, DNA is wrapped around an octamer of core histones to form nucleosomes. H1 binds to the linker DNA of nucleosome to form the chromatosome, the next structural unit of chromatin. Structural features on individual chromatosomes contribute to chromatin structure, but not fully characterized.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Physics and Astronomy and Center for Quantitative Biology, Rutgers University, Piscataway, New Jersey 08854, USA.
Nucleosomes are fundamental units of chromatin in which a length of genomic DNA is wrapped around a histone octamer spool in a left-handed superhelix. Large-scale nucleosome maps show a wide distribution of DNA wrapping lengths, which in some cases are tens of base pairs (bp) shorter than the 147 bp canonical wrapping length observed in nucleosome crystal structures. Here, we develop a thermodynamic model that assumes a constant free energy cost of unwrapping a nucleosomal bp.
View Article and Find Full Text PDFBMB Rep
January 2025
Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan (44919), Republic of Korea.
The nucleosome is the fundamental structural unit of chromosome fibers. A DNA wraps around a histone octamer to form a nucleosome, while neighboring nucleosomes interact to form higher-order structures and fit gigabase-long DNAs into a small volume of the nucleus. Nucleosomes interrupt the access of transcription factors to a genomic region, and provide regulatory controls of gene expression.
View Article and Find Full Text PDFNat Commun
January 2025
Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, 518132, China.
Nucleosome is the basic structural unit of the genome. During processes like DNA replication and gene transcription, the conformation of nucleosomes undergoes dynamic changes, including DNA unwrapping and rewrapping, as well as histone disassembly and assembly. However, the wrapping characteristics of nucleosomes across the entire genome, including region-specificity and their correlation with higher-order chromatin organization, remains to be studied.
View Article and Find Full Text PDFSubcell Biochem
December 2024
Department of Physics of the Condensed Matter, Universitat de Barcelona, Barcelona, Spain.
All matter must obey the general laws of physics and living matter is not an exception. Viruses have not only learnt how to cope with them but have managed to use them for their own survival. In this chapter, we will review some of the exciting physics that are behind viruses and discuss simple physical models that can shed some light on different aspects of the viral life cycle and viral properties.
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