Glutathione S-transferases and their interacting protein partners: a computational perspective

Aim: Glutathione S-transferase enzymes participates in detoxification of endogenous and exogenous electrophiles and in other cellular processes, such as electrophilic agents induced stress and growth factor-induced signaling, proliferation, differentiation, and apoptosis. This study is aimed to scrutinize the interaction of predominantly expressed GST isoforms (A1, A2, P1, M1, M2, M5 and T1) with two key partners of stress induced apoptotic pathway i.e. apoptosis signal-regulating kinase 1 (ASK1) and mitogen-activated protein kinase (MAPK8) using computational methods. Methods: The following computational workflow was implemented to predict the binding affinity of GST isoforms towards ASK1 and MAPK8. 1. Preparation of input sequence and structure dataset using UniProt and PDB databases. 2. Phylogenetic analysis of seven GST isoforms using Clustal Omega and MEGA to assess the evolutionary relationship. 3. String protein sequence search to construct the functional interactome for seven GSTs isoforms. 4. Preparation of the protein structures using MGL-ADT Tools. 5. Docking of GSTs with ASK1, MAPK8 using HADDOCK. 6. Prediction of hot spot regions of GSTs by in silico alanine scanning mutagenesis using DrugScorePPI. 7. Analysis of protein-protein docking results using PRODIGY, PDBSum and PyMOL. 8. Molecular dynamics simulation (MD) of GSTs with ASK1, MAPK8 using Gromacs. 9. Analysis and interpretation of MD results using PyMOL and GRACE. Results: Highest degree of homology was observed in two sub groups (SG) of GSTs. GSTA1, A2, P1 constituted SG1 and SG2 had GSTM1, M2 and M5. GSTT1 completely diverged from rest of the isoforms. GSTM family members exhibited higher binding affinity towards both MAPK8 as well as ASK1 followed by others.Whereas GSTP family also had higher binding affinity for ASK1 followed by others. Conclusion: GSTM family members exhibited higher binding affinity towards MAPK8 and ASK1 indicating their potential role in cellular processes other than metabolism