High-throughput mapping of the chromatin structure of human promoters

Our understanding of how chromatin structure influences cellular processes such as transcription and replication has been limited by a lack of nucleosome-positioning data in human cells. We describe a high-resolution microarray approach combined with an analysis algorithm to examine nucleosome positioning in 3,692 promoters within seven human cell lines. Unlike unexpressed genes without transcription-preinitiation complexes at their promoters, expressed genes or genes containing preinitiation complexes exhibit characteristic nucleosome-free regions at their transcription start sites. The combination of these nucleosome data with chromatin immunoprecipitation-chip analyses reveals that the melanocyte master regulator microphthalmia-associated transcription factor (MITF) predominantly binds nucleosome-free regions, supporting the model that nucleosomes limit sequence accessibility. This study presents a global view of human nucleosome positioning and provides a high-throughput tool for analyzing chromatin structure in development and disease.