Salicylaldehyde ester-mediated protein semi-synthesis enables studies on the tetra-acetylation of HMGB1

Abstract

ABSTRACTTo answer how protein post-translational modifications (PTMs) affect protein function, conformation, stability, localization and interaction with binders remains important in the biological study. However, the related study has been dramatically hindered by the difficulty in obtaining homogenous proteins with site-specific PTMs of interest. Herein, we introduce a protein semi-synthesis strategy via salicylaldehyde ester-mediated chemical ligations (Ser/Thr ligation and Cys/Pen ligation). This methodology has enabled us to generate Lys (2/6/7/11) tetra-acetylated HMGB1 (high-mobility group box 1) protein, a 25 kDa proinflammatory protein, in high purity. Further studies revealed that the tetra-acetylation may represent a regulatory switch to control the HMGB1 signaling pathway by abolishing its interaction with lipopoly-saccharide (LPS) and accelerating its degradation, consequently preventing cells from pyroptosis and lethality upon infectious injury.