核小體是真核染色質(zhì)的基本重復(fù)單元，核小體的組織對(duì)于基因調(diào)控極為重要,。Kaplan等人通過測(cè)量基因組范圍內(nèi)所存在的聚集在純化的酵母基因組DNA上的核小題,，而對(duì)核小體對(duì)于DNA序列的內(nèi)在偏好的重要性進(jìn)行了測(cè)試。他們獲得的分布圖與活體中核小體分布圖驚人地相似,，表明活體中核小體的組織在很大程度上是由生物體內(nèi)基因組DNA 序列決定的,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 458, 362-366 (19 March 2009) | doi:10.1038/nature07667;
The DNA-encoded nucleosome organization of a eukaryotic genome
Noam Kaplan1,9, Irene K. Moore3,9, Yvonne Fondufe-Mittendorf3, Andrea J. Gossett4, Desiree Tillo5, Yair Field1, Emily M. LeProust6, Timothy R. Hughes5,7,8, Jason D. Lieb4, Jonathan Widom3 & Eran Segal1,2
1 Department of Computer Science and Applied Mathematics,
2 Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
3 Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, 2153 Sheridan Road, Evanston, Illinois 60208, USA
4 Department of Biology, Carolina Center for Genome Sciences, and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
5 Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
6 Agilent Technologies Inc., Genomics—LSSU, 5301 Stevens Creek Boulevard, MS 3L/MT Santa Clara, California 95051, USA
7 Terrence Donnelly Centre for Cellular & Biomolecular Research,
8 Banting and Best Department of Medical Research, 160 College Street, Toronto, Ontario M5S 3E1, Canada
9 These authors contributed equally to this work.
Correspondence to: Jonathan Widom3Eran Segal1,2 Correspondence and requests for materials should be addressed to J.W. & E.S.
Nucleosome organization is critical for gene regulation1. In living cells this organization is determined by multiple factors, including the action of chromatin remodellers2, competition with site-specific DNA-binding proteins3, and the DNA sequence preferences of the nucleosomes themselves4, 5, 6, 7, 8. However, it has been difficult to estimate the relative importance of each of these mechanisms in vivo 7, 9, 10, 11, because in vivo nucleosome maps reflect the combined action of all influencing factors. Here we determine the importance of nucleosome DNA sequence preferences experimentally by measuring the genome-wide occupancy of nucleosomes assembled on purified yeast genomic DNA. The resulting map, in which nucleosome occupancy is governed only by the intrinsic sequence preferences of nucleosomes, is similar to in vivo nucleosome maps generated in three different growth conditions. In vitro, nucleosome depletion is evident at many transcription factor binding sites and around gene start and end sites, indicating that nucleosome depletion at these sites in vivo is partly encoded in the genome. We confirm these results with a micrococcal nuclease-independent experiment that measures the relative affinity of nucleosomes for 40,000 double-stranded 150-base-pair oligonucleotides. Using our in vitro data, we devise a computational model of nucleosome sequence preferences that is significantly correlated with in vivo nucleosome occupancy in Caenorhabditis elegans. Our results indicate that the intrinsic DNA sequence preferences of nucleosomes have a central role in determining the organization of nucleosomes in vivo.
