Notes: The p300/CBP-associate factor (PCAF) interacts with histone H3.3 through the Brd domain and is dysregulated in multiple disease states. Here, the co-crystal structure and biochemical analysis of a novel PCAF inhibitor, L-45, is presented. The disruption of the histone H3.3-PCAF interaction is monitored using the NanoBRET Target Engagement assay. Additionally, L45 has low cytotoxicity and good cell-permeability. (5123)

Notes: The BRD9 subunit of the SWI-SNF chromatin-remodeling complex is investigated in the context of aberrant cell proliferation in acute myeloid leukemia. Specifically, the NanoBRET system was used to measure the interactions of BRD9 and Histone H3.3. A small molecule inhibitor of the BRB9 bromodomain function, BI-7273, was further assessed in HEK293T cells. Disruption of BRB9 interaction with Histone H3.3 was confirmed at sub-micromolar concentrations of BI-7273. Cell viability in the presence of inhibitor was determined using the CellTiter-Glo System. (5079)

Notes: This paper introduces NanoBRET technology, which provides an improved alternative to conventional BRET protein interaction assays. NanoBRET assays combine the extremely bright NanoLuc luciferase with a means for tagging intracellular proteins with a long-wavelength fluorophore (HaloTag). The greater light intensity and improved spectral resolution of the NanoBRET assay results in increased detection sensitivity and dynamic range over current BRET technologies. Performance of the assay is demonstrated using several model systems, and the ability to image BRET in individual cells is illustrated. The  authors also demonstrate the application of NanoBRET in a novel assay developed for analyzing the interactions of bromodomain proteins with chromatin in living cells. (4575)