A functional role identified for conserved charged residues at the active site entrance of lipoxygenase with double specificity

作者：Alberti Jean Christophe; Mariani Magali; de Caraffa Virginie Brunini Bronzini; Gambotti Claude; Oliw Ernst H; Berti Liliane; Maury Jacques^*

来源：Journal of Molecular Catalysis B: Enzymatic , 2016, 123: 167-173.

DOI：10.1016/j.molcatb.2015.10.011

• Lipoxygenases
• Lipid peroxidation
• Mutagenesis
• Olea europaea L.

Plant lipoxygenases (LOXs) are a class of widespread dioxygenases catalyzing the hydroperoxidation of free polyunsaturated fatty acids, producing 9-hydroperoxides or 13-hydroperoxides from linoleic and alpha-linolenic acids, and are called 9-LOX or 13-LOX, respectively. Some LOXs produce both 9- and 13- hydroperoxides. The models proposed to explain the reaction mechanism specificity fail to explain the "double specificity" character of these LOXs. In this study, we used the olive LOX1 with double specificity to investigate the implication of the charged residues R265, R268, and K283 in the orientation of the substrate into the active site. These residues are present in a conserved pattern around the entrance of the active site. Our results show that these residues are involved in the penetration of the substrate into the active site: this positive patch could capture the carboxylate end of the substrate, and then guide it into the active site. Due to its position on alpha 2 helix, the residue K283 could have a more important role, its interaction with the substrate facilitating the motions of residues constituting the "cork of lipoxygenases" or the alpha 2 helix, by disrupting putative hydrogen and ionic bonds.

• 出版日期2016-1