Utilizing mass spectrometry-based targeted quantitative proteomics to determine the factors that alter the specificity of lysine acetyltransferases

摘要

Our targeted MS-based technique can quantitatively measure the acetylation on individual lysines of histones and determine the enzyme specificity for individual sites. We demonstrate that H3 is a preferred substrate for Rtt109-Vps75 acetylation, and H4 is primarily targeted by Piccolo NuA4. In addition, H3K9 and H3K23 are the only two residues found acetylated under Rtt109-Vps75 steady-state acetylation conditions, no matter what the histone conformation is. However, the site selectivity of Piccolo NuA4 is altered with different histone complexes. Rtt109-Vps75 prefers to acetylate H3 monomer, but Piccolo NuA4 prefers to catalyze NCP. Both histone chaperones and pre-existing histone marks can affect KAT site specificity.