Celastrol inhibits the Myb-KIX interaction. (A) The principle of bacterial autodisplay is shown on the left. A recombinant autotransporter in the outer membrane (o.m.) of E coli exposes the KIX (blue) domain on the bacterial surface, where it can bind a soluble Myb-GFP fusion protein. The domain structures of p300, the KIX-AIDA-I autotransporter, Myb, and the bacterial eGFP/Myb protein are shown on the right. DBD and TA, DNA-binding and transactivation domains of Myb; KIX, Br, HAT, and E1A refer to the KIX-, bromo-, and histone acetyltransferase domains and the E1A binding region of p300, respectively; SP, signal peptide; PAS passenger, linker, and β-barrel, the functional domains of the autotransporter. Binding experiments using bacteria expressing the KIX domain on the surface. Bacteria were incubated with eGFP/Myb or with eGFP (B), with wild-type or L302A mutant eGFP/Myb fusion proteins (C), or with wild-type eGFP/Myb fusion protein in the absence or presence of 1 μM Celastrol (D). Molecular docking studies. (E) The position of the LXXLL containing α-helix of Myb in the Myb-KIX complex is shown schematically. (F) The docking of Celastrol to the same surface of the KIX domain. The colors indicate the electrostatic potential of the binding surface (blue, positive; red, negative). (G) The interactions between Celastrol and Lys-568 and Glu-645 are highlighted.