© 2018 Elsevier B.V. Leukotrienes (LT) are lipid mediators of the inflammatory response that play key roles in diseases such as asthma and atherosclerosis. The precursor leukotriene A 4 (LTA 4 ) is synthesized from arachidonic acid (AA) by 5‑lipoxygenase (5-LOX), a membrane-associated enzyme, with the help of 5‑lipoxygenase-activating protein (FLAP), a nuclear transmembrane protein. In lipoxygenases the main chain carboxylate of the C-terminus is a ligand for the non-heme iron and thus part of the catalytic center. We investigated the role of a lysine-rich sequence (KKK 653–655 ) 20 amino acids upstream of the C-terminus unique to 5-LOX that might displace the main-chain carboxylate in the iron coordination sphere. A 5-LOX mutant in which KKK 653–655 is replaced by ENL was transfected into HEK293 cells in the absence and presence of FLAP. This mutant gave ~20-fold higher 5-LOX product levels in stimulated HEK cells relative to the wild-type 5-LOX. Co-expression of the enzymes with FLAP led to an equalization of 5-LOX products detected, with wild-type 5-LOX product levels increased and those from the mutant enzyme decreased. These data suggest that the KKK motif limits 5-LOX activity and that this attenuated activity must be compensated by the presence of FLAP as a partner protein for effective LT biosynthesis.
Publication Source (Journal or Book title)
Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Schexnaydre, E., Gerstmeier, J., Garscha, U., Jordan, P., Werz, O., & Newcomer, M. (2019). A 5‑lipoxygenase-specific sequence motif impedes enzyme activity and confers dependence on a partner protein. Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids, 1864 (4), 543-551. https://doi.org/10.1016/j.bbalip.2018.09.011