Understanding the Molecular Mechanism of the Ala-versus-Gly Concept Controlling the Product Specificity in Reactions Catalyzed by Lipoxygenases: A Combined Molecular Dynamics and QM/MM Study of Coral 8R-Lipoxygenase

TY - JOUR

T1 - Understanding the Molecular Mechanism of the Ala-versus-Gly Concept Controlling the Product Specificity in Reactions Catalyzed by Lipoxygenases

T2 - A Combined Molecular Dynamics and QM/MM Study of Coral 8R-Lipoxygenase

AU - Saura, Patricia

AU - Suardíaz, Reynier

AU - Masgrau, Laura

AU - González-Lafont, Àngels

AU - Rosta, Edina

AU - Lluch, José M.

PY - 2017/5/9

Y1 - 2017/5/9

N2 - Lipoxygenases (LOXs) are a family of enzymes that catalyze the highly specific hydroperoxidation of polyunsaturated fatty acids, such as arachidonic acid. Different stereo- or/and regioisomer hydroperoxidation products lead later to different metabolites that exert opposite physiological effects in the animal body and play a central role in inflammatory processes. The Gly-Ala switch of a single residue is crucial for the stereo- and regiocontrol in many lipoxygenases. Herein, we have combined molecular dynamics simulations with quantum mechanics/molecular mechanics calculations to study the hydrogen abstraction step and the molecular oxygen addition step of the hydroperoxidation reaction of arachidonic acid catalyzed by both wild-type Coral 8R-LOX and its Gly427Ala mutant. We have obtained a detailed molecular understanding of this Ala-versus-Gly concept. In wild type, molecular oxygen adds to C8 of arachidonic acid with an R stereochemistry. In the mutant, Ala427 pushes Leu385, blocks the region over C8, and opens an oxygen access channel now directed to C12, where molecular oxygen is added with an S stereochemistry. Thus, the specificity turns out to be dramatically inverted. Since Leu385 is highly conserved among many lipoxygenase isoforms, this mechanism can be general, and we propose that the presence of such type of bulky and hydrophobic residues can be key in controlling the extreme regio- and stereospecificity of lipoxygenases and, as a consequence, their physiological effects.

AB - Lipoxygenases (LOXs) are a family of enzymes that catalyze the highly specific hydroperoxidation of polyunsaturated fatty acids, such as arachidonic acid. Different stereo- or/and regioisomer hydroperoxidation products lead later to different metabolites that exert opposite physiological effects in the animal body and play a central role in inflammatory processes. The Gly-Ala switch of a single residue is crucial for the stereo- and regiocontrol in many lipoxygenases. Herein, we have combined molecular dynamics simulations with quantum mechanics/molecular mechanics calculations to study the hydrogen abstraction step and the molecular oxygen addition step of the hydroperoxidation reaction of arachidonic acid catalyzed by both wild-type Coral 8R-LOX and its Gly427Ala mutant. We have obtained a detailed molecular understanding of this Ala-versus-Gly concept. In wild type, molecular oxygen adds to C8 of arachidonic acid with an R stereochemistry. In the mutant, Ala427 pushes Leu385, blocks the region over C8, and opens an oxygen access channel now directed to C12, where molecular oxygen is added with an S stereochemistry. Thus, the specificity turns out to be dramatically inverted. Since Leu385 is highly conserved among many lipoxygenase isoforms, this mechanism can be general, and we propose that the presence of such type of bulky and hydrophobic residues can be key in controlling the extreme regio- and stereospecificity of lipoxygenases and, as a consequence, their physiological effects.

KW - Ala-versus-Gly concept

KW - arachidonic acid

KW - coral 8R-lipoxygenase

KW - enzyme catalysis

KW - free energy calculations

KW - molecular dynamics simulations

KW - QM/MM calculations

UR - http://www.scopus.com/inward/record.url?scp=85024869694&partnerID=8YFLogxK

U2 - 10.1021/acscatal.7b00842

DO - 10.1021/acscatal.7b00842

M3 - Article

AN - SCOPUS:85024869694

SN - 2155-5435

VL - 7

SP - 4854

EP - 4866

JO - ACS Catalysis

JF - ACS Catalysis

IS - 7

ER -