1. Cryo-EM structures of human arachidonate 12S-lipoxygenase bound to endogenous and exogenous inhibitors
- Author
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Mobbs, Jesse I, Black, Katrina A, Tran, Michelle, Burger, Wessel AC, Venugopal, Hariprasad, Holman, Theodore R, Holinstat, Michael, Thal, David M, and Glukhova, Alisa
- Subjects
Biochemistry and Cell Biology ,Biological Sciences ,Hematology ,Clinical Research ,Development of treatments and therapeutic interventions ,5.1 Pharmaceuticals ,United States ,Humans ,Cryoelectron Microscopy ,Platelet Activation ,Arachidonic Acid ,Arachidonate 12-Lipoxygenase ,Thrombocytopenia ,Cardiorespiratory Medicine and Haematology ,Clinical Sciences ,Paediatrics and Reproductive Medicine ,Immunology ,Biochemistry and cell biology ,Cardiovascular medicine and haematology ,Paediatrics - Abstract
Human 12-lipoxygenase (12-LOX) is a key enzyme involved in platelet activation, and the regulation of its activity has been targeted for the treatment of heparin-induced thrombocytopenia. Despite the clinical importance of 12-LOX, the exact mechanisms by which it affects platelet activation are not fully understood, and the lack of structural information has limited drug discovery efforts. In this study, we used single-particle cryo-electron microscopy to determine high-resolution structures (1.7-2.8 Å) of human 12-LOX. Our results showed that 12-LOX can exist in multiple oligomeric states, from monomer to hexamer, which may affect its catalytic activity and membrane association. We also identified different conformations within the 12-LOX dimer, which likely represent different time points in its catalytic cycle. Furthermore, we identified small molecules bound to 12-LOX. The active site of the 12-LOX tetramer was occupied by an endogenous 12-LOX inhibitor, a long-chain acyl coenzyme A. In addition, we found that the 12-LOX hexamer can simultaneously bind to arachidonic acid and ML355, a selective 12-LOX inhibitor that has passed a phase 1 clinical trial for the treatment of heparin-induced thrombocytopenia and received a fast-track designation by the Food and Drug Administration. Overall, our findings provide novel insights into the assembly of 12-LOX oligomers, their catalytic mechanism, and small molecule binding, paving the way for further drug development targeting the 12-LOX enzyme.
- Published
- 2023