Redox Potentials of Disulfide Bonds in LOXL2 Studied by Nonequilibrium Alchemical Simulation.

Lirui Lin,Li-Yan Xu,Wenjin Li,Haiying Zou,Geng Dong,En-Min Li

doi:10.3389/fchem.2021.797036

Lirui Lin, Li-Yan Xu + Show 4 more

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https://doi.org/10.3389/fchem.2021.797036

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Abstract

Lysyl oxidase-like 2 (LOXL2) is a metalloenzyme that catalyzes the oxidative deamination ε-amino group of lysine. It is found that LOXL2 is a promotor for the metastasis and invasion of cancer cells. Disulfide bonds are important components in LOXL2, and they play a stabilizing role for protein structure or a functional role for regulating protein bioactivity. The redox potential of disulfide bond is one important property to determine the functional role of disulfide bond. In this study, we have calculated the reduction potential of all the disulfide bonds in LOXL2 by non-equilibrium alchemical simulations. Our results show that seven of seventeen disulfide bonds have high redox potentials between −182 and −298 mV and could have a functional role, viz., Cys573–Cys625, Cys579–Cys695, Cys657–Cys673, and Cys663–Cys685 in the catalytic domain, Cys351–Cys414, Cys464–Cys530, and Cys477–Cys543 in the scavenger receptor cysteine-rich (SRCR) domains. The disulfide bond of Cys351–Cys414 is predicted to play an allosteric function role, which could affect the metastasis and invasion of cancer cells. Other functional bonds have a catalytic role related to enzyme activity. The rest of disulfide bonds are predicted to play a structural role. Our study provides an important insight for the classification of disulfide bonds in LOXL2 and can be utilized for the drug design that targets the cysteine residues in LOXL2.

Highlights

Lysyl oxidase like 2 (LOXL2) is a copper-dependent amine oxidase enzyme, which belongs to the lysyl oxidase (LOX) family (Smith-Mungo and Kagan, 1998; Jourdan-Le Saux et al, 1999; Csiszar, 2001)
The reduction potentials for the five disulfide bonds in the catalytic domain are correlated with the distances between the locations of disulfide bonds and catalytic site of metal Zn, i.e., short distance (5∼18 Å) corresponds to a high reduction potential (−182∼−298 mV) which corresponds to a functional role
The allosteric function of the disulfide bond in Lysyl oxidase-like 2 (LOXL2) corresponds to the ability of metastasis and invasion of cancer cells, and the catalytic function corresponds to the enzyme activity

Summary

Introduction

Lysyl oxidase like 2 (LOXL2) is a copper-dependent amine oxidase enzyme, which belongs to the lysyl oxidase (LOX) family (Smith-Mungo and Kagan, 1998; Jourdan-Le Saux et al, 1999; Csiszar, 2001). It catalyzes the oxidation of collagen and elastin to promote cross-linking, leading to the stiffening of the extracellular matrix (ECM) (Smith-Mungo and Kagan, 1998). Aside from its basic enzyme function, LOXs are found to be significant to human diseases, e.g., several types of cancer (Kagan, 2000; Barker, Cox, and Erler, 2012; Johnston and Lopez, 2018). Many studies are targeting LOXL2 to inhibit the metastasis/invasion of cancer (Hutchinson et al, 2017; Chopra et al, 2020; Klepfish et al, 2020)

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