Double mutation at the subunit interface of glutathione transferase rGSTM1-1 results in a stable, folded monomer.


Abstract

Canonical glutathione (GSH) transferases are dimeric proteins with subunits composed of an N-terminal GSH binding region (domain 1) and a C-terminal helical region (domain 2). The stabilities of several GSH transferase dimers are dependent upon two groups of interactions between domains 1 and 2 of opposing subunits: a hydrophobic ball-and-socket motif and a buried charge cluster motif. In rGSTM1-1, these motifs involve residues F56 and R81, respectively. The structural basis for the effects of mutating F56 to different residues on dimer stability and function has been reported (Codreanu et al. (2005) Biochemistry 44, 10605-10612). Here, we show that the simultaneous disruption of both motifs in the F56S/R81A mutant causes complete dissociation of the dimer to a monomeric protein on the basis of gel filtration chromatography and multiple-angle laser light scattering. The fluorescence and far-UV CD properties of the double mutant as well as the kinetics of amide H/D exchange along the polypeptide backbone suggest that the monomer has a globular structure that is similar to a single subunit in the native protein. However, the mutant monomer has severely impaired catalytic activity, suggesting that the dimer interface is vital for efficient catalysis. Backbone amide H/D exchange kinetics in the F56S and F56S/R81A mutants indicate that a reorganization of the loop structure between helix alpha2 and strand beta3 near the active site is responsible for the decreased catalytic activity of the monomer. In addition, the junction between the alpha4 and alpha5 helices in F56S/R81R shows decreased H/D exchange, indicating another structural change that may affect catalysis. Although the native subunit interface is important for dimer stability, urea-induced unfolding of the F56S/R81A mutant suggests that the interface is not essential for the thermodynamic stability of individual subunits. The H/D exchange data reveal a possible molecular basis for the folding cooperativity observed between domains 1 and 2. Study holds ProTherm entries: 19845 Extra Details: 1 mM EDTA and 0.02% NaH3 were added in the experiment GSH binding region; hydrophobic ball-and-socket motif; catalytic activity; folding cooperativity

Submission Details

ID: yxbYfgAG4

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:52 p.m.

Version: 1

Publication Details
Thompson LC;Walters J;Burke J;Parsons JF;Armstrong RN;Dirr HW,Biochemistry (2006) Double mutation at the subunit interface of glutathione transferase rGSTM1-1 results in a stable, folded monomer. PMID:16475815
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P
 

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)


Relevant PDB Entries

Structure ID Release Date Resolution Structure Title
6GSV 1996-11-08 1.75 FIRST-SPHERE AND SECOND-SPHERE ELECTROSTATIC EFFECTS IN THE ACTIVE SITE OF A CLASS MU GLUTATHIONE TRANSFERASE
2GST 1993-10-31 1.8 STRUCTURE OF THE XENOBIOTIC SUBSTRATE BINDING SITE OF A GLUTATHIONE S-TRANSFERASE AS REVEALED BY X-RAY CRYSTALLOGRAPHIC ANALYSIS OF PRODUCT COMPLEXES WITH THE DIASTEREOMERS OF 9-(S-GLUTATHIONYL)-10-HYDROXY-9, 10-DIHYDROPHENANTHRENE
6GSU 1996-11-08 1.85 FIRST-SPHERE AND SECOND-SPHERE ELECTROSTATIC EFFECTS IN THE ACTIVE SITE OF A CLASS MU GLUTATHIONE TRANSFERASE
6GSW 1996-11-08 1.85 FIRST-SPHERE AND SECOND-SPHERE ELECTROSTATIC EFFECTS IN THE ACTIVE SITE OF A CLASS MU GLUTATHIONE TRANSFERASE
3GST 1993-10-31 1.9 STRUCTURE OF THE XENOBIOTIC SUBSTRATE BINDING SITE OF A GLUTATHIONE S-TRANSFERASE AS REVEALED BY X-RAY CRYSTALLOGRAPHIC ANALYSIS OF PRODUCT COMPLEXES WITH THE DIASTEREOMERS OF 9-(S-GLUTATHIONYL)-10-HYDROXY-9, 10-DIHYDROPHENANTHRENE
4GST 1993-10-31 1.9 REACTION COORDINATE MOTION IN AN SNAR REACTION CATALYZED BY GLUTATHIONE TRANSFERASE
6GSX 1996-11-08 1.91 FIRST-SPHERE AND SECOND-SPHERE ELECTROSTATIC EFFECTS IN THE ACTIVE SITE OF A CLASS MU GLUTATHIONE TRANSFERASE
5GST 1993-10-31 2.0 REACTION COORDINATE MOTION IN AN SNAR REACTION CATALYZED BY GLUTATHIONE TRANSFERASE
5FWG 1999-01-27 2.0 TETRA-(5-FLUOROTRYPTOPHANYL)-GLUTATHIONE TRANSFERASE
1MTC 2003-03-25 2.2 GLUTATHIONE TRANSFERASE MUTANT Y115F
6GST 1996-11-08 2.2 FIRST-SPHERE AND SECOND-SPHERE ELECTROSTATIC EFFECTS IN THE ACTIVE SITE OF A CLASS MU GLUTATHIONE TRANSFERASE
3FYG 1999-06-01 2.2 CRYSTAL STRUCTURE OF TETRADECA-(3-FLUOROTYROSYL)-GLUTATHIONE S-TRANSFERASE
6GSY 1996-11-08 2.2 FIRST-SPHERE AND SECOND-SPHERE ELECTROSTATIC EFFECTS IN THE ACTIVE SITE OF A CLASS MU GLUTATHIONE TRANSFERASE
1GSB 1993-10-31 2.5 NEW CRYSTAL FORMS OF A MU CLASS GLUTATHIONE S-TRANSFERASE FROM RAT LIVER
1GSC 1993-10-31 2.5 NEW CRYSTAL FORMS OF A MU CLASS GLUTATHIONE S-TRANSFERASE FROM RAT LIVER

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
93.1 Glutathione S-transferase Mu 1 P10649 GSTM1_MOUSE
100.0 Glutathione S-transferase Mu 1 P04905 GSTM1_RAT