Covalent modification of the NH2-terminal tails of the core histones (H2A, H2B, H3, and H4), the proteins that make up the bulk of chromatin in eukaryotes, play an important role in modulating chromatin function. For example, acetylation of histone tails plays a role in transcription, and phosphorylation has been implicated in chromosome condensation. The role of histone methylation has been less well characterized. Wang et al. now show that the enzyme PRMT1 (a protein arginine methyltransferase) methylates the Arg3 residue in H4 tails in vivo (see the Protocol by Mowen and David). Methylation of Arg3 enhances subsequent acetylation at lysine residues 5, 8, 12, and/or 16 by the histone acetyltransferase p300, but prior acetylation of these residues inhibits methylation, which suggests that the different modifications are coordinated temporally. Furthermore, H4 methylation facilitates the activation of transcription, providing further evidence for a histone "code."
H. Wang, Z.-Q. Huang, L. Xia, O. Feng, H. Erdjument-Bromage, B. D. Strahl, S. D. Briggs, C. D. Allis, J. Wong, P. Tempst, Y. Zhang, Methylation of histone H4 at arginine 3 facilitating transcriptional activation by nuclear hormone receptor. Science 293, 853-857 (2001). [Abstract] [Full Text]
K. A. Mowen, M. David, Analysis of protein arginine methylation and protein arginine-methyltransferase activity. Science's STKE (2001), http://stke.sciencemag.org/cgi/content/full/OC_sigtrans;2001/93/pl1. [Abstract] [Full Text]