Unique Protein Interaction Networks Define The Chromatin Remodeling Module of The NuRD Complex

The combination of four proteins and their paralogues including MBD2/3, GATAD2A/B, CDK2AP1, and CHD3/4/5, which we refer to as the MGCC module, form the chromatin remodeling module of the Nucleosome Remodeling and Deacetylase (NuRD) complex, a gene repressor complex. Specific paralogues of the MGCC subunits such as MBD2 and CHD4 are amongst the key repressors of adult-stage fetal globin and provide important targets for molecular therapies in beta (β)-thalassemia. However, mechanisms by which the MGCC module acquires paralogue-specific function and specificity have not been addressed to date. Understanding the protein-protein interaction (PPI) network of the MGCC subunits is essential in defining underlying mechanisms and developing treatment strategies. Therefore, using pulldown followed by mass spectrometry analysis (PD-MS) we report a proteome-wide interaction network of the MGCC module in a paralogue-specific manner. Our data also demonstrate that the disordered C-terminal region of CHD3/4/5 is a gateway to incorporate remodeling activity into both the ChAHP (CHD4, ADNP, HP1γ) and NuRD complexes in a mutually exclusive manner. We define a short aggregation prone region (APR) within the C-terminal segment of GATAD2B that is essential for the interaction of CHD4 and CDK2AP1 with the NuRD complex. Finally, we also report an association of CDK2AP1 with the Nuclear Receptor Co-Repressor (NCOR) complex. Overall, this study provides insight into the possible mechanisms through which the MGCC module can achieve specificity and diverse biological functions.