In silico analysis of mutations occurring in the protein N-acetylgalactosamine-6-sulfatase (GALNS) and causing mucopolysaccharidosis IVA

The goals were to analyze and characterize the secondary structure, regions of intrinsic disorder and physicochemical characteristics of three classes of mutations described in the enzyme N-acetylgalactosamine-6-sulfatase that cause mucopolysaccharidosis IVA: missense mutations, insertions and deletions. All mutations were compared to wild-type enzyme, and the results showed that with 25 of 129 missense mutations secondary structure was maintained and that 104 mutations showed minor changes, such as an increase or decrease in the size of the elements. The secondary structure of all insertions and deletions introduced important changes, such as increase in the number and size of elements. The results obtained from intrinsic disorder analysis revealed that missense mutations caused no alterations. However, the insertions and deletions led to major regions of intrinsic disorder. The physicochemical characteristics of the amino acids found in missense mutations revealed unchanged characteristics in 32 of the 129 mutations. However, the remainder had changes that could lead to a modification of tertiary structure. The results proved that it was feasible and necessary to obtain the three-dimensional structure of the enzyme with its mutants to better understand the change in function.