5fno
Manganese Lipoxygenase
Structural highlights
FunctionMNLOX_PYRO7 Lipoxygenase that metabolizes linoleic and alpha-linolenic acids to 9S-, 11- and 13R-hydroperoxy fatty acids. At the end of lipoxygenation, the intermediate product 11S-HPODE from linoleic acid is then transformed into 9S-HPODE and 13R-HPODE as the final products. The intermediate product 11R-HPOTrE from alpha-linolenic acid is transformed into 9S-HPOTrE and 13R-HPOTrE as the final products. 9S-HPOTrE is further oxidized by the enzyme to 9S,16S-DiHPOTrE as the end product.[1] Publication Abstract from PubMedLipoxygenases (LOX) are non-heme metal enzymes, which oxidize polyunsaturated fatty acids to hydroperoxides. All LOX belong to the same gene family, and they are widely distributed. LOX of animals, plants and prokaryotes contain Fe as the catalytic metal, whereas fungi express LOX with Fe or with Mn. Little is known about metal selection by LOX and the adjustment of the redox potentials of their protein-bound catalytic metals. Thirteen 3D structures of animal, plant, and prokaryotic FeLOX are available but none of MnLOX. The MnLOX of the most important plant pathogen, the rice blast fungus Magnaporthe oryzae (Mo), was expressed in Pichia pastoris. Mo-MnLOX was deglycosylated, purified to homogeneity, and subjected to crystal screening and X-ray diffraction. The structure was solved by sulfur and manganese single-wavelength anomalous dispersion to a resolution of 2.0 A. The Mn coordinating sphere is similar to Fe ligands of coral 8R-LOX and soybean LOX-1, but not overlapping. The Asn473 is positioned on a short loop (AsnGlnGlyGluPro) instead of an alpha-helix and forms hydrogen bonds with Gln281. Comparison with Fe-LOX suggest that Phe332 and Phe525 might contribute to the unique suprafacial hydrogen abstraction and oxygenation mechanism of Mo-MnLOX by controlling oxygen access to the pentadiene radical. Modeling suggests that Arg525 is positioned close to Arg182 of 8R-LOX, and both residues likely tether the carboxylate group of the substrate. An oxygen channel could not be identified. We conclude that Mo-MnLOX illustrates a partly unique variation of the structural theme of FeLOX. Crystal Structure of Manganese Lipoxygenase of the Rice Blast Fungus Magnaporthe oryzae.,Wennman A, Oliw EH, Karkehabadi S, Chen Y J Biol Chem. 2016 Jan 18. pii: jbc.M115.707380. PMID:26783260[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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