Abstract 1377: Set7 is a novel histone methyltransferase inSchizosaccharomyces Pombe

Dynamics and plasticity of chromatin regulation is mediated by a molecular ballet of writers, readers and erasers of epigenetic marks on both DNA and histones. The pattern of histone modifications may define a histone code, which is part of intricate networks that ultimately regulate transcriptional events. Dysfunction of histone methylation affects chromatin regulation and is involved in an increasing number of pathologies from cellular transformation to tumor progression and other diseases. However, histone methyltransferase (HMTase) pathways remain to be further explored and better understood. Fission yeast (Schizosaccharomyces pombe) is an ideal model organism to investigate the fundamental mechanisms of chromatin dynamics. Fission yeast possesses 13 SET-containing proteins (Set1 to 13), several of which methylate histones or ribosomes. The catalytic SET domain is highly conserved across eukaryotes (e.g. Set2, a homologue of the oncoprotein NSD2/MMSET/WHSC1 in human). Structure-function studies of HMTases are essential from basic science to translational research. However, full-length structures of fission yeast methyltransferases are still scarce. Here, in a bid to better understand histone methylation and to gain insight for drug-design, we report the identification and structural characterization of a novel histone methyltransferase Set7 (SPCC297.04c), in Schizosaccharomyces Pombe. In this study, we investigated Sp.Set7’s cellular localization and the effect of Sp.Set7 knock-out on the cell cycle and sporulation. Next, we elucidated Sp.Set7’s Lysine substrate specificity on histone H3 and H4 by biochemical assays and mass spectrometry. Finally, we solved the X-ray structure of the apo Sp.Set7 at 2.0 A resolution. In summary, we report the biochemical and structural characterization of a novel histone methyltransferase in fission yeast, which has implications for better understanding the fundamental mechanism of HMTases. Citation Format: Eric Di Luccio, Yunpeng Shen, Damiaan E.H.F Mevius, Yeon Jeong Noh, Jihyeon Kim, Masayo Morishita. Set7 is a novel histone methyltransferase in Schizosaccharomyces Pombe [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1377. doi:10.1158/1538-7445.AM2017-1377