Crystal structure of linoleate 13R-manganese lipoxygenase in complex with an adhesion protein

The crystal structure of 13R-manganese lipoxy-genase (MnLOX) of Gaeumannomyces graminis (Gg) in complex with zonadhesin of Pichia pastoris was solved by molecular replacement. Zonadhesin contains beta-strands in two subdomains. A comparison of Gg-MnLOX with the 9S-MnLOX of Magnaporthe oryzae (Mo) shows that the protein fold and the geometry of the metal ligands are conserved. The U-shaped active sites differ mainly due to hydrophobic residues of the substrate channel. The volumes and two hydrophobic side pockets near the catalytic base may sanction oxygenation at C-13 and C-9, respectively. Gly-332 of Gg-MnLOX is positioned in the substrate channel between the entrance and the metal center. Replacements with larger residues could restrict oxygen and substrate to reach the active site. C-18 fatty acids are likely positioned with C-11 between Mn2+ OH2 and Leu-336 for hydrogen abstraction and with one side of the 12Z double bond shielded by Phe-337 to prevent antarafacial oxygenation at C-13 and C-11. Phe-347 is positioned at the end of the substrate channel and replacement with smaller residues can position C-18 fatty acids for oxygenation at C-9.(jlr) Gg-MnLOX does not catalyze the sequential lipoxygenation of n-3 fatty acids in contrast to Mo-MnLOX, which illustrates the different configurations of their substrate channels.-Chen, Y., A. Wennman, S. Karkehabadi, angstrom. Engstrom, and E. H. Oliw. Crystal structure of linoleate 13R-manganese lipoxygenase in complex with an adhesion protein.