A Statistical–Mechanical Model for Regulation of Long-range Chromatin Structure and Gene Expression

✍ Scribed by HARUHIKO ISHII

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 265 KB
• Volume: 203
• Category: Article
• ISSN: 0022-5193
• DOI: 10.1006/jtbi.2000.1081

✦ Synopsis

In eukaryotic organisms, organization of chromatin is considered to play a role in transcriptional regulation by limiting the accessibility of a gene to the transcription machinery. It is not fully understood, however, how chromatin around a particular locus can be speci"cally altered to allow transcription. This paper introduces a statistical}mechanical model of chromatin to illustrate a potential mechanism. The model, which is mathematically equivalent to the onedimensional Ising model of magnetic systems, explains how gene regulatory DNA sequences can a!ect the chromatin structure over a long distance in cis. The main assumption of the model is cooperativity of histone H1 in binding to the nucleosome array. This cooperativity results in a long-range correlation of histone H1 distribution along the chromatin. Due to this long-range correlation, a gene regulatory element, such as a transcriptional enhancer, may lead to depletion of histone H1 over a large region of chromatin thereby increasing the accessibility of the gene. The model provides a mechanism for a sensitive genetic switch and explains several aspects of gene regulation and chromatin structure.