NMR Molecular Replacement Provides New Insights into Binding Modes to Bromodomains of BRD4 and TRIM24 br

Structure-based drug discovery (SBDD) largely relies on structural information from X-ray crystallography because tradi-tional NMR structure calculation methods are too time consuming tobe aligned with typical drug discovery timelines. The recentlydeveloped NMR molecular replacement (NMR2) method dramaticallyreduces the time needed to generate ligand-protein complexstructures using published structures (apo or holo) of the targetprotein and treating all observed NOEs as ambiguous restraints,bypassing the laborious process of obtaining sequence-specificresonance assignments for the protein target. We apply this methodto two therapeutic targets, the bromodomain of TRIM24 and thesecond bromodomain of BRD4. We show that theNMR2method-ology can guide SBDD by rationalizing the observed SAR. We alsodemonstrate that new types of restraints and selective methyl labeling have the potential to dramatically reduce"time to structure"and extend the method to targets beyond the reach of traditional NMR structure elucidation