Catalytic Convergence of Manganese and Iron Lipoxygenases by Replacement of a Single Amino Acid

Abstract

Background: 13R-MnLOX catalyzes suprafacial hydrogen abstraction and oxygenation in contrast to sLOX-1. Results: Mutation of one residue of 13R-MnLOX altered hydrogen abstraction and oxygenation to antarafacial. Conclusion: Replacement with the corresponding residue of soybean LOX-1 yielded catalytic convergence. Significance: The suprafacial oxygenation mechanism can be attributed to a single amino acid substitution.

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

“…The 11(R/S)-and 11S-HETE were from Cayman. Hydroperoxides of 18:2n-6 and 18:3n-3 were prepared as described (11,19). Morpheus protein crystallization screen was from Molecular Dimensions.…”

“…Interestingly, the Pro-288 residue is not conserved in other MnLOX. A Thr residue is found at this position of Fo-MnLOX and often a Gly residue in FeLOX, but insertion of a Thr or Gly residue between His-290 and His-294 of Gg-MnLOX at the corresponding position of Pro-288 inactivated the enzyme (19). A summary of the effects of replacement of residues in the active site of Gg-MnLOX is shown in Table 2.…”

“…b This mutation increases the biosynthesis of epoxyalcohols, but has little effect on the regiospecificity (17). c These mutations increase the relative oxygenation at C-9 of 18:2n-6 (19). d This mutation shifts the direction of oxygen insertion but retains the steric abstraction of the hydrogen (19).…”

“…Gg-MnLOX has been extensively studied since 1998 as the prototype MnLOX (12)(13)(14)(15). The enzyme has been characterized by site-directed mutagenesis of residues, which were chosen from sequence homology to FeLOXs with known 3D structures or from sequence differences between MnLOXs with dissimilar catalytic activities (9)(10)(11)(16)(17)(18)(19). The three dimensional structure of Gg-MnLOX might provide additional information of these tentative key residues and their importance for the catalytic activities of Gg-MnLOX and related MnLOXs (9-11, 16, 19, 20).…”

Expression of Fusion Proteins of Aspergillus terreus Reveals a Novel Allene Oxide Synthase

“…8R-DOX of A. fumigatus oxygenates the 9-trans-12-cis isomer of 18:2 by hydrogen abstraction at C-11 and oxygenation at C-9 to 9R-HPODE as the main metabolite (44), and replacement of one amino acid of 10R-DOX shifts oxygenation from C-10 to C-8 (37). In addition, the suprafacial hydrogen abstraction and oxygenation by 9S-MnLOX can be altered by a single amino acid replacement (53).…”