PROTEOME-WIDE ANALYSIS OF LYSINE 2-HYDROXYISOBUTYRYLATION IN DEVELOPING RICE (ORYZA SATIVA) SEEDS REVEALS UNIQUE SEQUENCE FEATURE OF MODIFICATION SITES AND FUNCTIONS IN SEED DEVELOPMENT

Zhaohua Peng

Biochemistry, Molecular Biology, Entomology, Plant Pathology, Mississippi State University, Mississippi, USA

Abstract

Lysine 2-hydroxyisobutyrylation is a recently identified protein post-translational modification that is known to affect the association between histone and DNA. However, non-histone protein lysine 2-hydroxyisobutyrylation remain largely unexplored. Using antibody-based affinity enrichment of 2-hydroxyisobutyrylation peptides and nano-HPLC/MS/MS analysis, we identified 9,916 2-hydroxyisobutyryl lysine sites on 2,512 proteins in developing rice seeds, representing the first lysine 2-hydroxyisobutyrylome dataset. Functional annotation analyses indicated that a wide variety of vital biological processes were preferably targeted by lysine 2-hydroxyisobutyrylation, including glycolysis/gluconeogenesis, TCA cycle, starch biosynthesis, lipid metabolism, protein biosynthesis and processing. Our finding showed that most 2-hydroxyisobutyryl sites identified were unique to lysine 2-hydroxyisobutyrylation compared to lysine acetylation and succinylation, suggesting the existence of specific establishment mechanism and cellular functions of the 2-hydroxyisobutyrylated proteins. Analysis of the lysine 2-hydroxyisobutyrylation sites found that the modification sites were highly sequence specific and had less surface accessibility compared with other lysine residues. Our study provides the first systematic analysis of lysine 2-hydroxyisobutyrylation proteome and serves as an important resource for further investigation of the regulatory mechanisms and functions of lysine 2-hydroxyisobutyrylation.

Keywords: Posttranslational modification, seed developement, lysine 2-hydroxyisobutyrylation, rice.