Macrocycle screening against the C-terminal region of CHD4 uncovers its role as an interaction hub in the formation of the nucleosome remodeling and deacetylase complex

Abstract

The Nucleosome Remodeling and Deacetylase complex (NuRD) plays a key role in regulating hemoglobin expression in adult erythroid cells. Selectively disrupting this complex potently induces the expression of fetal hemoglobin, a proven therapeutic strategy for treating beta-hemoglobinopathies such as sickle cell anemia. In these studies, we have used mRNA display to identify small macrocyclic peptides that inhibit the interaction between two core components of NuRD, the SANT-SLIDE domain of CHD4 and the CR2 domain of GATAD2A. In addition, the screen suggested a second binding site on the CHD4 domain. Based on this observation, we hypothesized and confirmed that CDK2AP1 bound to this region of CHD4, leading us to purify and determine the structure of the ternary complex between CHD4, GATAD2A, and CDK2AP1. The results of our studies show that the SANT-SLIDE domain of CHD4 functions as a critical interaction hub in the formation of NuRD and suggest a strategy to block NuRD function for therapy.