title: A surface mutant (G82R) of a human alpha-glutathione S-transferase shows decreased thermal stability and a new mode of molecular association in the crystal.
abstract: A chimeric enzyme (GST121) of the human alpha-glutathione S-transferases GST1-1 and GST2-2, which has improved catalytic efficiency and thermostability from its wild-type parent proteins, has been crystallized in a space group that is isomorphous with that reported for crystals of GST1-1. However, a single-site (G82R) mutant of GST121, which exhibits a significant reduction both in vitro and in vivo in protein thermostability, forms crystals that are not isomorphous with GST1-1. The mutant protein crystallizes in space group P2(1)2(1)2(1), with cell dimensions a = 49.5, b = 92.9, c = 115.9 A, and one dimer per asymmetric unit. Preliminary crystallographic results show that a mutation of the surface residue Gly 82 from a neutral to a charged residue causes new salt bridges to be formed among the GST dimers, suggesting that the G82R mutant might aggregate more readily than does GST121 in solution, resulting in a change of its solution properties.
authors.affiliation: Department of Crystallography and Biological Sciences, University of Pittsburgh, Pennsylvania 15260.
authors.forename: K
authors.initials: K
authors.lastname: Zeng
authors.forename: J P
authors.initials: JP
authors.lastname: Rose
authors.forename: H C
authors.initials: HC
authors.lastname: Chen
authors.forename: C L
authors.initials: CL
authors.lastname: Strickland
authors.forename: C P
authors.initials: CP
authors.lastname: Tu
authors.forename: B C
authors.initials: BC
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D003460:Crystallization; D018360:Crystallography, X-Ray; D005982:Glutathione Transferase / Q000737:chemistry / Q000235:genetics*; D006358:Hot Temperature; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011489:Protein Denaturation; D011993:Recombinant Fusion Proteins / Q000737:chemistry
chemical_list: D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase