Computational analysis of human N-acetylgalactosamine-6-sulfate sulfatase enzyme: an update in genotype–phenotype correlation for Morquio A

Abstract

Mucopolysaccharidosis IV A (MPS IV A) is a lysosomal storage disease produced by the deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS) enzyme. Although genotype-phenotype correlations have been reported, these approaches have not enabled to establish a complete genotype-phenotype correlation, and they have not considered a ligand-enzyme interaction. In this study, we expanded the in silico evaluation of GALNS mutations by using several bioinformatics tools. Tertiary GALNS structure was modeled and used for molecular docking against galactose-6-sulfate, N-acetylgalactosamine-6-sulfate, keratan sulfate, chondroitin-6-sulfate, and the artificial substrate 4-methylumbelliferyl-β-D-galactopyranoside-6-sulfate. Furthermore, we considered the evolutionary residue conservation, change conservativeness, position within GALNS structure, and the impact of amino acid substitution on the structure and function of GALNS. Molecular docking showed that amino acids involved in ligand interaction correlated with those observed in other human sulfatases, and mutations within the active cavity reduced affinity of all evaluated ligands. Combination of several bioinformatics approaches allowed to explaine 90% of the missense mutations affecting GALNS, and the prediction of the phenotype for another 21 missense mutations. In summary, we have shown for the first time a docking evaluation of natural and artificial ligands for human GALNS, and proposed an update in genotype-phenotype correlation for Morquio A, based on the use of multiple parameters to predict the disease severity.

Advances in the Development of Pharmacological Chaperones for the Mucopolysaccharidoses

“…Molecular characterization of LSDs has shown that in most of the cases the disease is caused by missense mutations [37,38]. Pathophysiological studies in different LSDs have suggested that in some cases, the amino acid change leads to loss of protein stability due to changes in their processing, folding, glycosylation, and pH stability, which promotes aggregation and can induce ER or Golgi apparatus retention and/or increased degradation, or defective transport to the lysosomes [37][38][39][40][41][42][43][44][45][46][47][48]. In this sense, the use of PCs as an alternative to restore the folding and trafficking of the mutated lysosomal proteins has been proposed [19,20].…”

“…Based on results from a modeled GALNS and computational dockings for natural and artificial substrates, a virtual screening strategy against 11,421 compounds tested in humans (ZINC In Man, a special subset of ZINC [94]), was designed to identify a set of compounds that bind to the active cavity of the enzyme. Ezetimibe and pranlukast ( Figure 1B,C) were selected among the top 20 interacting compounds and were predicted to establish similar interactions to those modeled for KS and C6S, and the artificial GALNS substrate [48,93] (Figure 1D). Ezetimibe is an approved drug that blocks intestinal cholesterol absorption by selectively inhibiting Niemann-Pick C1-like 1 protein and is indicated for treatment of disorders with elevated cholesterol levels [48].…”

“…Ezetimibe and pranlukast ( Figure 1B,C) were selected among the top 20 interacting compounds and were predicted to establish similar interactions to those modeled for KS and C6S, and the artificial GALNS substrate [48,93] (Figure 1D). Ezetimibe is an approved drug that blocks intestinal cholesterol absorption by selectively inhibiting Niemann-Pick C1-like 1 protein and is indicated for treatment of disorders with elevated cholesterol levels [48]. Pranlukast is an orally administered, selective, and competitive cysteinyl leukotriene type 1 receptor antagonist, indicated for the treatment of bronchial asthma in pediatric and adult patients [95].…”

“…Pranlukast is an orally administered, selective, and competitive cysteinyl leukotriene type 1 receptor antagonist, indicated for the treatment of bronchial asthma in pediatric and adult patients [95]. In terms of safety, both drugs are well tolerated and have adverse event profiles similar to placebo [48,95].…”

Pharmacological Chaperones for the Mucopolysaccharidoses

“…Molecular characterization of LSDs has shown that in most of the cases the disease is caused by missense mutations [37,38]. Pathophysiological studies in different LSDs have suggested that in some cases, the amino acid change leads to loss of protein stability due to changes in their processing, folding, glycosylation, and pH stability, which promotes aggregation and can induce ER or Golgi apparatus retention and/or increased degradation, or defective transport to the lysosomes [37][38][39][40][41][42][43][44][45][46][47][48]. In this sense, it has been proposed the use of PC as an alternative to restore the folding and trafficking of the mutated lysosomal proteins [19,20].…”