Structure-guided inhibitor design for human FAAH by interspecies active site conversion

• Published in: Proceedings of the National Academy of Sciences - PNAS 2008-09, Vol.105 (35), p.12820-12824
• Main Authors: Mileni, Mauro, Johnson, Douglas S, Wang, Zhigang, Everdeen, Daniel S, Liimatta, Marya, Pabst, Brandon, Bhattacharya, Keshab, Nugent, Richard A, Kamtekar, Satwik, Cravatt, Benjamin F, Ahn, Kay, Stevens, Raymond C
• Format: Article
• Language: English
• Subjects: Active sites; AMIDES; Amidohydrolases - antagonists & inhibitors; Amidohydrolases - chemistry; Anilides - chemistry; Animals; Binding Sites; Biochemistry; Biological Sciences; CARBOXYLIC ACIDS; Catalysis - drug effects; CONVERSION; CRYSTAL STRUCTURE; Crystallography, X-Ray; DESIGN; Drug Design; DRUGS; Endocannabinoids; ENZYME INHIBITORS; Enzyme Inhibitors - chemistry; Enzyme Inhibitors - pharmacology; ENZYMES; Fatty acids; Gene expression; GENETICS; Genotype & phenotype; HUMAN POPULATIONS; Humans; HYDROLASES; INACTIVATION; INTEGRALS; Kinetics; LIPIDS; MATERIALS SCIENCE; MEMBRANES; Models, Molecular; MUTAGENESIS; Piperidines - chemistry; Protein Engineering; Protein Structure, Secondary; PROTEINS; RATS; RECEPTORS; Research and development; Rodents; SENSITIVITY; SIDE EFFECTS; Species Specificity; THERAPEUTIC USES
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0806121105

The integral membrane enzyme fatty acid amide hydrolase (FAAH) hydrolyzes the endocannabinoid anandamide and related amidated signaling lipids. Genetic or pharmacological inactivation of FAAH produces analgesic, anxiolytic, and antiinflammatory phenotypes but not the undesirable side effects of direct cannabinoid receptor agonists, indicating that FAAH may be a promising therapeutic target. Structure-based inhibitor design has, however, been hampered by difficulties in expressing the human FAAH enzyme. Here, we address this problem by interconverting the active sites of rat and human FAAH using site-directed mutagenesis. The resulting humanized rat (h/r) FAAH protein exhibits the inhibitor sensitivity profiles of human FAAH but maintains the high-expression yield of the rat enzyme. We report a 2.75-Å crystal structure of h/rFAAH complexed with an inhibitor, N-phenyl-4-(quinolin-3-ylmethyl)piperidine-1-carboxamide (PF-750), that shows strong preference for human FAAH. This structure offers compelling insights to explain the species selectivity of FAAH inhibitors, which should guide future drug design programs.