Structural characterization of the catalytic domain of the human 5-lipoxygenase enzyme.
Leukotrienes are inflammatory mediators involved in several diseases. The enzyme 5-lipoxygenase initiates the synthesis of leukotrienes from arachidonic acid. Little structural information is available regarding 5-lipoxygenase. In this study, we found that the primary structure of the catalytic domain of human 5-lipoxygenase is similar to that of the rabbit 15-lipoxygenase. This similarity allowed the development of a theoretical model of the tertiary structure of the 5-lipoxygenase catalytic domain, using the resolved structure of rabbit 15-lipoxygenase as a template. This model was used in conjunction with primary and secondary structural information to investigate putative nucleotide binding sites, a MAPKAP kinase 2 phosphorylation site, and a Src homology 3 binding site on the 5-lipoxygenase protein, further. Results indicate that the putative nucleotide binding sites are spatially distinct, with one on the beta-barrel domain and the other(s) on the catalytic domain. The MAPKAP kinase 2 phosphorylation site involves a four amino acid insertion in mammalian 5-lipoxygenases that significantly alters molecular structure. This target for post-translational modification is both common and unique to 5-lipoxygenases. The Src homology 3 binding site, found in all lipoxygenases, appears to lack the characteristic left-handed type II helix structure of known Src homology 3 binding sites. These results, which highlight the unique nature of the MAPKAP kinase site, underscore the utility of structural information in the analysis of protein function.
Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of Michigan Health System, 6301 MSRB III, Ann Arbor, MI 48109-0642, USA.
Jason
J
Hemak
David
D
Gale
Thomas G
TG
Brock
D000595:Amino Acid Sequence; D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000737:chemistry*; D020134:Catalytic Domain; D017124:Conserved Sequence; D006801:Humans; D008969:Molecular Sequence Data; D015394:Molecular Structure; D017434:Protein Structure, Tertiary; D011817:Rabbits; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D001094:Arachidonate 5-Lipoxygenase