Fig. 1
From: Natural product derivative Gossypolone inhibits Musashi family of RNA-binding proteins
Gossypolone disrupts Musashi-numb RNA binding and directly binds to RBD1 of MSI1. a Gossypolone (Gn) was identified as a potential MSI1 inhibitor through an initial FP-based drug screening. Top panel: Dose-response curves of Gn and its inactive analog MP-Gr in Full length MSI1 (MSI1-FL) or RNA Binding Domain 1 (aa 20–107) of MSI1 (MSI1-RBD1) to Numb RNA. Bottom panel: Dose-response curves of Gn and MP-Gr in Full length MSI2 (MSI2-FL) or RNA Recognition Motif 1 (aa 20–107) of MSI2 (MSI2-RRM1) to Numb RNA. Ki values were calculated based on the Kd and the dose-response curves. b SPR analyses of Gn binding to immobilized GB1-tagged MSI1-RBD1. Higher response unit (RU) is a result of more binding events. c Overlay of 2D 1H-15N HSQC spectra of 15N-MSI1-RBD1 (black) titrated with Gn. Four RNA binding residues (boxed) undergo line broadening upon addition of Gn indicating that they are involved in binding to Gn. d Docked model of MSI1 RBD1 bound to gossypolone. The protein atoms are shown as spheres. The gossypolone structure is shown as sticks. The four MSI1-RBD1 RNA binding residues that undergo significant shifts are highlighted in yellow (F23, W29, F65 and K93). This figure was prepared using PyMOL. e Gn dose-response CETSA in HCT-116 β/W cell lysate (n = 2) with one representative western blot