7TTL

Stable-5-LOX elongated Ha2 (4 copies ASU)

Summary for 7TTL

• Entry DOI: 10.2210/pdb7ttl/pdb
• Descriptor: Arachidonate 5-lipoxygenase, FE (II) ION (3 entities in total)
• Functional Keywords: lipoxygenase, dioxygenase, membrane-binding, oxidoreductase
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 4
• Total formula weight: 317968.35

Authors

Gilbert, N.C.,Newcomer, M.E. (deposition date: 2022-02-01, release date: 2022-08-31, Last modification date: 2023-10-18)

Primary citation

Gallegos, E.M.,Reed, T.D.,Mathes, F.A.,Guevara, N.V.,Neau, D.B.,Huang, W.,Newcomer, M.E.,Gilbert, N.C.
Helical remodeling augments 5-lipoxygenase activity in the synthesis of proinflammatory mediators.
J.Biol.Chem., 298:102282-102282, 2022

PubMed Abstract: The synthesis of proinflammatory leukotrienes implicated in asthma, allergic rhinitis, and atherosclerosis is initiated by the enzyme 5-lipoxygenase (5-LOX). The crystal structure of human Stable-5-LOX revealed a conformation where the catalytic iron was inaccessible to bulk solvent as two aromatic residues on a conserved helix-α2 (Hα2) plugged the substrate access portal. Whether 5-LOX can also adopt a more open conformation has not been resolved. Here, we present a new conformation of 5-LOX where Hα2 adopts an elongated conformation equivalent to that described in other animal lipoxygenase structures. Our observation of the sigmoidal kinetic behavior of 5-LOX, which is indicative of positive cooperativity, is consistent with a substrate-induced conformational change that shifts the ensemble of enzyme populations to favor the catalytically competent state. Strategic point mutations along Hα2 designed to unlock the closed conformation and elongate Hα2 resulted in improved kinetic parameters, altered limited proteolysis data, and a drastic reduction in the length of the lag phase yielding the most active Stable-5-LOX to date. Structural predictions by AlphaFold2 of these variants statistically favor an elongated Hα2 and reinforce a model in which improved kinetic parameters correlate with a more readily adopted open conformation. Taken together, these data provide valuable insights into the synthesis of leukotrienes.

PubMed: 35863431
DOI: 10.1016/j.jbc.2022.102282

Experimental method

X-RAY DIFFRACTION (2.43 Å)