Mechanistic and Structural Insights into Histone H2A-H2B Chaperone in Chromatin Regulation

Histone chaperones include a wide variety of proteins which associate with histones and regulate chromatin structure. The classic H2A-H2B type of histone chaperones, and the chromatin remodeling complex components possessing H2A-H2B chaperone activity, show a broad range of structures and functions. Rapid progress in the structural and functional study of H2A-H2B chaperones extends our knowledge about the epigenetic regulation of chromatin. In this review, we summarize the most recent advances in the understanding of the structure and function of H2A-H2B chaperones that interact with either canonical or variant H2A-H2B dimers. We discuss the current knowledge of the H2A-H2B chaperones, which present no preference for canonical and variant H2A-H2B dimers, describing how they interact with H2A-H2B to fulfill their functions. We also review recent advances of H2A variant-specific chaperones, demarcating how they achieve specific recognition for histone variant H2A.Z and how these interactions regulate chromatin structure by nucleosome editing. We highlight the universal mechanism underlying H2A-H2B dimers recognition by a large variety of histone chaperones. These findings will shed insight into the biological impacts of histone chaperone, chromatin remodeling complex, and histone variants in chromatin regulation.