Systematic Analysis of Yeast F-box Proteins Reveals a New Role of Ubiquitination in Polarity Establishment

Abstract

DNA is wrapped around a histone protein bundle, and these histone proteins can undergo post-translational modifications which then participate in signaling pathways to regulate important cellular functions. One such histone modification is methylation, where lysine can be mono, di, or tri-methylated. Reader proteins bind to methyl lysine and serve as docking sites for additional proteins that alter gene expression or chromatin structure. Dysregulation of histone methylation has been associated with certain types of cancer; therefore, it is necessary to understand the driving forces for binding of methylated lysine by these reader proteins to aid the development of reader protein probes or inhibitors with the desired specificity. In this project, the cation- interaction between trimethylated lysine 9 (Kme3) of H3 and the Drosophila reader protein, HP1 chromodomain, is investigated. The binding site of HP1 is comprised of three aromatic amino acids, two tyrosine residues and a tryptophan. To better understand the contribution of tryptophan in this cation-π binding event, an unnatural tryptophan analog is synthesized with 1 fluorine atom, which is highly electron-withdrawing, attached to the outer aromatic rung. Once synthesized, these unnatural analogs will then be inserted into the HP1 binding site. Comparative binding studies between the wild type and mutant protein with the Kme3 peptide will provide a better understanding of the cation-π mechanism. If Kme3 binds less tightly to the mutated binding pockets, it will indicate the importance of the tryptophan-π contribution to binding.Bachelor of Scienc