TAILIEUCHUNG - Báo cáo khoa học: Nucleosome positioning in relation to nucleosome spacing and DNA sequence-specific binding of a protein

Nucleosome positioning is an important mechanism for the regulation of eukaryotic gene expression. Folding of the chromatin fiber can influence nucleosome positioning, whereas similar electrostatic mechanisms govern the nucleosome repeat length and chromatin fiber folding in vitro. | ễFEBS Journal Nucleosome positioning in relation to nucleosome spacing and DNA sequence-specific binding of a protein Rama-Haritha Pusarla Vinesh Vinayachandran and Purnima Bhargava Centre for Cellular Molecular Biology Hyderabad India Keywords chromatin assembly ionic strength nucleosome positioning nucleosome spacing protein boundary Correspondence P. Bhargava Centre for Cellular Molecular Biology UppalRoad Hyderabad-500007 India Fax 91 40 27160591 Tel 91 40 27192603 E-mail purnima@ These authors contributed equally to this work Received 12 October 2006 revised 2 March 2007 accepted 7 March 2007 doi Nucleosome positioning is an important mechanism for the regulation of eukaryotic gene expression. Folding of the chromatin fiber can influence nucleosome positioning whereas similar electrostatic mechanisms govern the nucleosome repeat length and chromatin fiber folding in vitro. The position of the nucleosomes is directed either by the DNA sequence or by the boundaries created due to the binding of certain trans-acting factors to their target sites in the DNA. Increasing ionic strength results in an increase in nucleosome spacing on the chromatin assembled by the S-190 extract of Drosophila embryos. In this study a mutant lac repressor protein R3 was used to find the mechanisms of nucleosome positioning on a plasmid with three R3-binding sites. With increasing ionic strength in the presence of R3 the number of positioned nucleosomes in the chromatin decreased whereas the internucleosomal spacings of the positioned nucleosomes in a single register did not change. The number of the positioned nucleosomes in the chromatin assembled in vitro over different plasmid DNAs with 1-3 lac operators changed with the relative position and number of the R3-binding sites. We found that in the presence of R3 nucleosomes were positioned in the salt gradient method of the chromatin assembly even in the absence of a nucleosome-positioning .

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