The role of the glycine triad in human glutathione synthetase.
Experimental kinetics and computational modeling of human glutathione synthetase (hGS) support the significant role of the G-loop glycine triad (G369, G370, G371) for activity of this ATP-grasp enzyme. Enzyme kinetic experiments indicate that G369V and G370V mutant hGS have little activity (<0.7 and 0.3%, respectively, versus wild-type hGS). However, G371V retains ∼13% of the activity of wild-type hGS. With respect to G-loop:A-loop interaction in hGS, mutations at Gly369 and Gly370 decrease ligand binding and prevent active site closure and protection. This research indicates that Gly369 and Gly370 have essential roles in hGS, while Gly371 has a lesser involvement. Implications for glycine-rich ensembles in other phosphate-binding enzymes are discussed.
Dinescu
Adriana
A
Department of Chemistry, University of North Texas, Denton, TX 76203, United States.
Brown
Teresa R
TR
Barelier
Sarah
S
Cundari
Thomas R
TR
Anderson
Mary E
ME
D000595:Amino Acid Sequence; D005981:Glutathione Synthase / Q000737:chemistry* / Q000235:genetics; D005998:Glycine / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D009154:Mutation; D011487:Protein Conformation
D005981:Glutathione Synthase; D005998:Glycine
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