Structure, mechanism, and inhibition of Hedgehog acyltransferase

• DOI: 10.1016/j.molcel.2021.11.018
• Publication Date: 2021-12-09T15:56:27Z
• Authors: Claire E. Coupland; Sebastian A. Andrei; T. Bertie Ansell; Loic Carrique; Pramod Kumar; Lea Sefer; Rebekka A. Schwab; Eamon F.X. Byrne; Els Pardon; Jan Steyaert; Anthony I. Magee; Thomas Lanyon-Hogg; Mark S.P. Sansom; Edward W. Tate; Christian Siebold
• Keywords: 0301 basic medicine; Protein Conformation; Hedgehog acyl transferase; Acylation; Sonic Hedgehog signaling; CRYO-EM; Catalytic Domain; Chlorocebus aethiops; Enzyme Inhibitors; PALMITOYLATION; heme; 11 Medical and Health Sciences; REFINEMENT; Palmitoyl Coenzyme A; ALGORITHMS; drug; small molecule inhibitor; cryo-EM structure; 3. Good health; COS Cells; integral membrane protein; Life Sciences & Biomedicine; Signal Transduction; 570; Biochemistry & Molecular Biology; STRUCTURE VALIDATION; PROTEINS; 610; membrane-bound O-acyltransferase; Heme; Molecular Dynamics Simulation; Article; Structure-Activity Relationship; 03 medical and health sciences; Allosteric Regulation; Animals; Humans; Hedgehog Proteins; Science & Technology; IDENTIFICATION; Cryoelectron Microscopy; RECOGNITION; Membrane Proteins; Cell Biology; molecular dynamics simulations; 06 Biological Sciences; palmitoyl co enzyme A; HEK293 Cells; VISUALIZATION; Acyltransferases; GENERATION; Developmental Biology

The Sonic Hedgehog (SHH) morphogen pathway is fundamental for embryonic development and stem cell maintenance and is implicated in various cancers. A key step in signaling is transfer of a palmitate group to the SHH N terminus, catalyzed by the multi-pass transmembrane enzyme Hedgehog acyltransferase (HHAT). We present the high-resolution cryo-EM structure of HHAT bound to substrate analog palmityl-coenzyme A and a SHH-mimetic megabody, revealing a heme group bound to HHAT that is essential for HHAT function. A structure of HHAT bound to potent small-molecule inhibitor IMP-1575 revealed conformational changes in the active site that occlude substrate binding. Our multidisciplinary analysis provides a detailed view of the mechanism by which HHAT adapts the membrane environment to transfer an acyl chain across the endoplasmic reticulum membrane. This structure of a membrane-bound O-acyltransferase (MBOAT) superfamily member provides a blueprint for other protein-substrate MBOATs and a template for future drug discovery.