Structural Study Of Lysine Methyltransferase Set9 Regulatory Protein Pdp1 PWWP Domain In Fission Yeast

This dissertation is comprised of two chapters: the solution structure and itsinteraction research of the PWWP domain of Pdp1 which is a regulatory protein of thehistone lysine methyltransferase Set9 from Saccharomyces pombe, and the solutionstructure and the interaction research of human MOZ tandem PHD type zinc-finger,respectively. In each part, we firstly introduced the background and the significationof the work. Then, we presented the methods and results. At last, we made discussionsand conclusions.In the chapter one, we first introduced the background: the eukaryotic genome iscompacted into chromatin in different structural levels. Post-translationalmodifications of histone play important regulatory roles in chromatin structure andgene transcription. Different degrees of methylation on H4K20 are related to theprocesses of cell cycle, DNA damage repair, and heterochromatin maintenance. Infission yeast, Set9 is the only methyltransferase of H4K20 and Pdp1 is essential forSet9 localization on chromatin and methyl-transfer activity. In the methods and resultspart, we solved the solution structure of Pdp1 PWWP domain from Saccharomycespombe, and first identified Pdp1 PWWP domain binds specifically to trimethylatedH4K20 and non-specifically to dsDNA. We mapped their binding sites on thestructure, and further proposed the possible model of Pdp1 binding to chromatin. Thisresearch has proposed a new insight for further analysis of the role of PWWP domainin chromatin regulation.In the chapter two, we first introduced histone acetylation, and the role of thismodification in transcriptional activation. Bromodomain is the only knownacetyl-lysine recognition motif before Zeng et al. identified the function of the tandemPHD domain of DPF3b. Extensive research of single chromatin binding domain hasbeen done these years, while such tandem domains often exhibt different bindingproperties from single ones. The tandem PHD fingers of DPF3b is just like this. In themethods and results part, we solved the solution structures of human MOZ tandemPHD zinc-finger domain. Similar with that in DPF3b, MOZ tandem PHD fingerspecifically recognizes acetylated histone H3K14, which was identified by NMRperturbation experiments. But differently, MOZ tandem PHD finger cannot bind to histone H4K16ac. Through mutagenesis, we also found the key residues of MOZtandem PHD finger which are responsible for interacting with H4K14ac. Thesignificance of this study is the identification of the specific substrate of MOZ PHDfingers and providing information to the scientist who are investigating the function ofMOZ histone acetyltransferase in the epigenetic regulation.