Characterization of ASF1 and GCN5 in the ciliated protozoan tetrahymena thermophila

One method of regulating accessibility of DNA is chromatin remodelling via histone post-translational modifications (PTM). Adding an acetyl group to the lysine residues (K) on the core histone H3 is one of these chemical modifications. Acetylation of H3 on lysine 56 (H3K56ac) is an important histone alteration that is conserved among most if not all eukaryotes including humans. Several histone acetyl transferases (HAT) have been shown to be responsible for H3K56ac in different organisms including Gen5 and p300/CPB in human cells and Rtt109 in fungi including the yeast Saccharomyces cerevisiae. In addition the histone chaperone ASf1, is also required for these modifications in yeast and human cells. The ciliated protozoan Tetrahymena thermophila is an effective model organism for studying the function of histone PTMs in certain processes including meiosis and RNA interference. Here, I show that tGen5 has H3 acetylation activity and that tAsf1 binds Histone H3.