TAILIEUCHUNG - Báo cáo Y học: Use of site-specific recombination as a probe of nucleoprotein complex formation in chromatin Micha Schwikardi and Peter Droge ¨

DNA transactions in eukaryotes require that proteins gain access to target sequences packaged in chromatin. Further, interactions between distinct nucleoprotein complexes are often required to generate higher-order structures. Here, we employed two prokaryotic site-specific recombination systems to investigate how chromatin packaging affects the assembly of nucleoprotein structures of different complexities at more than 30 genomic loci. The dynamic nature of chromatin permitted protein–DNA and DNA–DNA interactions for sites of at least 34 bp in length. However, the assembly of higher-order nucleoprotein structures on targets spanning 114 bp was impaired. This impediment was maintained over at least 72 h and was. | Eur. J. Biochem. 268 6256-6262 2001 FEBS 2001 Use of site-specific recombination as a probe of nucleoprotein complex formation in chromatin Micha Schwikardi and Peter Droge Institute of Genetics University of Cologne Germany DNA transactions in eukaryotes require that proteins gain access to target sequences packaged in chromatin. Further interactions between distinct nucleoprotein complexes are often required to generate higher-order structures. Here we employed two prokaryotic site-specific recombination systems to investigate how chromatin packaging affects the assembly of nucleoprotein structures of different complexities at more than 30 genomic loci. The dynamic nature of chromatin permitted protein-DNA and DNA-DNA interactions for sites of at least 34 bp in length. However the assembly of higher-order nucleoprotein structures on targets spanning 114 bp was impaired. This impediment was maintained over at least 72 h and was not affected by the transcriptional status of chromatin nor by inhibitors of histone deacetylases and topoisomerases. Our findings suggest that nucleosomal linker-sized DNA segments become accessible within hours for protein binding due to the dynamic nature of chromatin. Longer segments however appear refractory for complete occupancy by sequence-specific DNA-binding proteins. The results thus also provide an explanation why simple recombination systems such as Cre and Flp are proficient in eukaryotic chromatin. Keywords chromatin DNA reactivity nucleoprotein complex site-specific recombination transcription. Alterations in chromatin structure are involved in the regulation of DNA transactions such as transcription and sitespecific recombination. Recently chromatin remodeling and histone acetylation deacetylation were identified as important regulators of chromatin structure at specific loci reviewed in 1-4 . Fundamental questions in this context concern the general reactivity of DNA sites packaged into chromatin. For example does the .

• Báo cáo khoa học
• Report medicine
• traditional medicine
• scientific reports
• oxidation
• Crystal structure
• bacteria
• medical knowledge
• medical research
• analysis of cytoplasmic
• hemoglobin
• medicine
• cell proliferation
• breast cancer
• chemical reaction
• gastric cancer
• hormone medicine
• tumor cells
• biochemical studies
• environmental medicine