Human glutathione synthetase (hGS) is a critically important enzyme responsible for catalyzing the synthesis of the key antioxidant glutathione. An obligate homodimer, hGS is negatively cooperative with respect to its ?-glutamylcysteine substrate. Within the active site of hGS, a sequence of conserved amino acids known as the E-Loop (Ala210 to Asn216) serves to bind and position the negatively cooperative substrate. Some E-Loop residues also interact with amino acids near the dimer interface, a relatively small region shown to be on the allosteric path of hGS.A computational exploration of this region provides insight into the origins of allostery. Molecular dynamics simulations of wild-type and mutant hGS elucidate the structural significance of the E-Loop residues, while extensive docking studies illustrate the critical aspects of both product and substrate binding. The computational work presented here complements the experimental data, explaining key interactions of the E-Loop and the wider impact this region has on the structural stability, activity and kinetics of hGS.Supported in part by NIH R15GM086833 (MEA), a Research Enhancement Program Grant (TWU, MEA), and UNT Faculty Research Grant (TRC).

Computational modeling of allostery and substrate binding in human glutathione synthetase

247th National Meeting (2014)

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