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Crystal structure of cytochrome P450 OleT H85Q in complex with arachidonic acid
Structural highlights
FunctionPublication Abstract from PubMedThe Jeotgalicoccus sp. peroxygenase cytochrome P450 OleTJE (CYP152L1) is a hydrogen peroxide-driven oxidase that catalyzes oxidative decarboxylation of fatty acids, producing terminal alkenes with applications as fine chemicals and biofuels. Understanding mechanisms that favor decarboxylation over fatty acid hydroxylation in OleTJE could enable protein engineering to improve catalysis or to introduce decarboxylation activity into P450s with different substrate preferences. In this manuscript, we have focused on OleTJE active site residues Phe(79), His(85), and Arg(245) to interrogate their roles in substrate binding and catalytic activity. His(85) is a potential proton donor to reactive iron-oxo species during substrate decarboxylation. The H85Q mutant substitutes a glutamine found in several peroxygenases that favor fatty acid hydroxylation. H85Q OleTJE still favors alkene production, suggesting alternative protonation mechanisms. However, the mutant undergoes only minor substrate binding-induced heme iron spin state shift toward high spin by comparison with WT OleTJE, indicating the key role of His(85) in this process. Phe(79) interacts with His(85), and Phe(79) mutants showed diminished affinity for shorter chain (C10-C16) fatty acids and weak substrate-induced high spin conversion. F79A OleTJE is least affected in substrate oxidation, whereas the F79W/Y mutants exhibit lower stability and cysteine thiolate protonation on reduction. Finally, Arg(245) is crucial for binding the substrate carboxylate, and R245E/L mutations severely compromise activity and heme content, although alkene products are formed from some substrates, including stearic acid (C18:0). The results identify crucial roles for the active site amino acid trio in determining OleTJE catalytic efficiency in alkene production and in regulating protein stability, heme iron coordination, and spin state. Catalytic Determinants of Alkene Production by the Cytochrome P450 Peroxygenase OleTJE.,Matthews S, Belcher JD, Tee KL, Girvan HM, McLean KJ, Rigby SE, Levy CW, Leys D, Parker DA, Blankley RT, Munro AW J Biol Chem. 2017 Mar 24;292(12):5128-5143. doi: 10.1074/jbc.M116.762336. Epub, 2017 Jan 4. PMID:28053093[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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