Abstract 2754: Affinity-based probe reveal Bim negatively regulates the chaperone functions of Hsp70, a non-Bcl-2 BH3 receptor

Abstract

Abstract The identification of novel non-Bcl-2 BH3 receptors is still challenge owing to frequently weak, transient and reversible binding character of the PPIs mediated by them. Herein, we designed and synthesized an affinity-based probe (AfBP), S1b-probe, by introducing a photo-crosslinker to an artificial BH3 mimetic. Hsp70 proteins were identified as novel BH3 receptors in situ. The PPIs between Bcl-2 proteins and Hsp70 proteins were further validated by fluorescent polarization (FP), isothermal titration calorimetry (ITC) and Co-immunoprecipitation (Co-IP) experiments. Structural and functional analysis by photo-crosslinking/LC-MS/MS sequencing, 1H-15N transverse relaxation optimized spectroscopy (TROSY-HSQC), trypsin proteolysis, single-turnover ATPase rates and denatured rhodanese aggregation measurement demonstrated that BimBH3 bind in the NBD domain of Hsp70 proteins to act as a co-chaperone that negatively regulates the ATPase activity and chaperone functions. S1g, derived from BH3 mimetics, was screened as a specific Hsp70 inhibitor in native physiological context by using S1b-probe. Citation Format: Ziqian Wang, Zhichao Zhang, Ting Song, Zongwei Guo. Affinity-based probe reveal Bim negatively regulates the chaperone functions of Hsp70, a non-Bcl-2 BH3 receptor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2754.