In silico mutational study reveal improved interaction between Beta-Hexosaminidase A and GM2 activator essential for the breakdown of GM2 and GA2 Gangliosides on Tay-Sachs disease

摘要

Gene Hex-A on chromosome 15 in human provides instructions for making subunit of an enzyme called Beta-Hexosaminidase A (BHA).Within lysosomes BHA forms part of a complex that breaks down a fatty substance called GM2 gangliosides. The mutation in BHA of Hex-A gene is unable to degrade GM2 gangliosides, causes Tay-Sach's disease.GM2 Activator (GM2A) a large binding pocket binds gangliosides and stimulates the breakdown of GM2 and GA2 gangliosides by BHA. The GSEP_(283) alpha loop of BHAis involved in GM2A binding. The aim of the present study is to represent and compare the interaction between BHA and GM2A proteins before and after mutation. The mutation Ser279Pro was performed using tool PyMOL and optimized using Arguslab with UFF force field. We used HADDOCK 2.2 server for protein-protein docking, SPDBV and PyMOL viewer software were used for understanding and analyzing the interaction. There were slight changes in the amino acid interactions at GSEP_(283) alpha loop region after mutation with decreasing binding energy when compared with unmutated protein. The docked results provided an evidence that the GSEP_(283) loop of BHA was binding to GM2A and we have represented for the first time a model on how the mutation on Hex-A affects GSEP_(283) interaction with GM2A activator. Our study also highlights that the TYR137 of GM2A is present in the surface that play role in lipid transfer. This in-silico study is a contribution for the research related to the interaction between BHA and GM2A proteins.