tailieunhanh - Báo cáo Y học: Nucleotide excision repair and chromatin remodeling

The organization of DNA within eukaryotic cell nuclei poses special problems and opportunities for the cell. For example, assembly of DNA into chromatin is thought to be a principle mechanism by which adventitious general transcription is repressed. However, access to genomic DNA for events such as DNA repair must be facilitated by energy-intensive processes that either directly alter chromatin structure or impart post-translational modifications, leading to increased DNA accessibility. | Eur. J. Biochem. 269 2288-2293 2002 FEBS 2002 doi MINIREVIEW Nucleotide excision repair and chromatin remodeling Kiyoe Ura1 and Jeffrey J. Hayes2 1 Division of Gene Therapy Science Osaka University School of Medicine Suita Osaka Japan 2Department of Biochemistry and Biophysics University of Rochester Medical Center Rochester NY USA The organization of DNA within eukaryotic cell nuclei poses special problems and opportunities for the cell. For example assembly of DNA into chromatin is thought to be a principle mechanism by which adventitious general transcription is repressed. However access to genomic DNA for events such as DNA repair must be facilitated by energy-intensive processes that either directly alter chromatin structure or impart post-translational modifications leading to increased DNA accessibility. The assembly of DNA into chromatin affects both the incidence of damage to DNA and repair of that damage. Correction of most damage to DNA caused by UV irradiation occurs via the nucleotide excision repair NER process. NER requires extensive involvement of large multiprotein complexes with relatively large stretches of DNA. Here we review recent evidence suggesting that at least some steps of NER require ATP-dependent chromatin remodeling activities while perhaps others do not. INTRODUCTION In vivo eukaryotic DNA is packaged with histones and other accessory proteins into chromatin. The assembly of nucleosomes the basic unit of chromatin changes the structure of DNA and restricts access of DNA binding factors to their recognition sites 1 . In particular DNA within the nucleosome is highly bent with w 150 bp of DNA wrapped in w 14 loops around a central spool consisting of the core histone proteins 2 3 . Although nucleosomal DNA is quite accessible to small molecules the DNA binding activity of larger molecules and complexes that require interaction with multiple base pairs is typically severely restricted within the .