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.
Hemak
Jason
J
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.
Gale
David
D
Brock
Thomas G
TG
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