LINKING HISTONE ACETYLATION TO TRANSCRIPTIONAL REGULATION

In eukaryotes, DNA is assembled with histones to form nucleosomes, the basic subunit of chromatin structure. The wrapping of DNA around hist one octamers to form nucleosomal filaments and further folding of thes e filaments are necessary to contain eukaryotic genomes within nuclei. However, the dense packing of chromatin in nuclei and the association of DNA with histones restrict the access of proteins involved ill gen e transcription to DNA. Abundant biochemical data supports a long-stan ding correlation between histone acetylation and gene activation, sugg esting that histone acetylation acts to enhance the access of transcri ption-associated proteins to DNA. However, despite this correlation, n uclear enzymes responsible for transcription-associated histone acetyl ation have been identified only recently. Here we review evidence sugg esting that histone acetylation represents a major pathway for transcr iptional regulation, and discuss possible roles for transcription-asso ciated histone acetyltransferases in this regulation.