Top-Down Mass Spectrometry Analysis of Histone Modifications in Sorghum during Drought Acclimation

This study explores the changes in histone modifications of sorghum bicolor through developmental stages and in response to drought stress in two sorghum genotypes. We analyzed the leaves of 48 plants using top-down mass spectrometry and identified 26 unique histone proteins and 677 unique histone proteoforms. We detected trimethylation on nearly all H2B N-termini where acetylation is commonly expected. In addition, an unexpected modification on H2A histones was assigned to N-pyruvic acid 2-iminylation based on its unique neutral loss of CO2.