DNA Structure

Cracking the Chromatin Code

Science's STKE  10 Apr 2001:
Vol. 2001, Issue 77, pp. tw10
DOI: 10.1126/stke.2001.77.tw10

Covalent modifications on the amino-terminal tails of the histone proteins are thought to be involved in the specification of higher-order chromatin structures that are intimately involved in processes such as gene transcription, DNA replication, and repair. For example, heterochromatin plays an important role in silencing gene expression. The protein Clr4 has been suggested to be involved in heterochromatin formation and can methylate the lysine-9 residue of the histone H3 tail. Nakayama et al. now show that Clr4-directed methylation of histone H3 corresponds with heterochromatin assembly in vivo, which is consistent with the role of Clr4 in epigenetic silencing. H3 methylation results in localization of Swi6, a homolog of the Drosophila heterochromatin protein 1. Furthermore, Clr3, a histone H3-specific deactylase, is also required for H3 methylation, Swi6 localization, and heterochromatin formation, supporting the hypothesis that a histone modification "code" exists for the establishment of chromatin structures. Berger provides an acompanying perspective.

J.-i. Nakayama, J. C. Rice, B. D. Strahl, C. D. Allis, S. I. S. Grewal, Role of histone H3 lysine 9 methylation in epigenetic control of heterochromatin assembly. Science 292, 110-113 (2001). [Abstract] [Full Text]

S. L. Berger, The histone modification circus. Science 292, 64-65 (2001). [Full Text]