Structural distortions due to missense mutations in human formylglycine-generating enzyme leading to multiple sulfatase deficiency

Abstract

The major candidate for multiple sulfatase deficiency is a defective formylglycine-generating enzyme (FGE). Though adequately produced, mutations in FGE stall the activation of sulfatases and prevent their activity. Missense mutations, viz. E130D, S155P, A177P, W179S, C218Y, R224W, N259I, P266L, A279V, C336R, R345C, A348P, R349Q and R349W associated with multiple sulfatase deficiency are yet to be computationally studied. Aforementioned mutants were initially screened through ws-SNPs&GO^3D program. Mutant R345C acquired the highest score, and hence was studied in detail. Discrete molecular dynamics explored structural distortions due to amino acid substitution. Therein, comparative analyses of wild type and mutant were carried out. Changes in structural contours were observed between wild type and mutant. Mutant had low conformational fluctuation, high atomic mobility and more compactness than wild type. Moreover, free energy landscape showed mutant to vary in terms of its conformational space as compared to wild type. Subsequently, wild type and mutant were subjected to single-model analyses. Mutant had lesser intra molecular interactions than wild type suggesting variations pertaining to its secondary structure. Furthermore, simulated thermal denaturation showed dissimilar pattern of hydrogen bond dilution. Effects of these variations were observed as changes in elements of secondary structure. Docking studies of mutant revealed less favourable binding energy towards its substrate as compared to wild type. Therefore, theoretical explanations for structural distortions of mutant R345C leading to multiple sulfatase deficiency were revealed. The protocol of the study could be useful to examine the effectiveness of pharmacological chaperones prior to experimental studies.

Keywords:

• discrete molecular dynamics
• lysosomal storage disorder
• free energy landscape
• multiple sulfatase
• genetic disorder
• misfolding

Abbreviations:

• ARSB, aryl sulfatase B
• AUC, area under the curve
• DMD, discrete molecular dynamics
• FEL, free energy landscape
• FGE, formylglycine-generating enzyme
• FGly, formylglycine
• LSD, lysosomal storage disorder
• MCC, Mathew’s correlation coeffecient
• MD, molecular dynamics
• MSD, multiple sulfatase defeciency
• PCA, principal component analysis
• PDB, Protein Data Bank
• PIC, protein interaction calculator
• RCSB, Research Collaboratory for Structural Bioinformatics
• RMSD, root mean square deviation
• RMSF, root mean square fluctuation
• RoG, radius of gyration
• SUMF1, sulfatase-modifying factor
• SVM-3D, support vector machine-3D

Acknowledgement

The authors of the manuscript thank VIT University for providing the infrastructure to carry out this research.