1B48

CRYSTAL STRUCTURE OF MGSTA4-4 IN COMPLEX WITH GSH CONJUGATE OF 4-HYDROXYNONENAL IN ONE SUBUNIT AND GSH IN THE OTHER: EVIDENCE OF SIGNALING ACROSS DIMER INTERFACE IN MGSTA4-4

Summary for 1B48

• Entry DOI: 10.2210/pdb1b48/pdb
• Descriptor: PROTEIN (GLUTATHIONE S-TRANSFERASE), 4-S-GLUTATHIONYL-5-PENTYL-TETRAHYDRO-FURAN-2-OL, GLUTATHIONE, ... (4 entities in total)
• Functional Keywords: glutathione s-transferase, gst, subunit cooperativity, transferase
• Biological source: Mus musculus (house mouse)
• Cellular location: Cytoplasm: P24472
• Total number of polymer chains: 2
• Total formula weight: 51724.32

Authors

Xiao, B.,Zimniak, P.,Ji, X. (deposition date: 1999-01-06, release date: 1999-09-29, Last modification date: 2023-08-30)

Primary citation

Xiao, B.,Singh, S.P.,Nanduri, B.,Awasthi, Y.C.,Zimniak, P.,Ji, X.
Crystal structure of a murine glutathione S-transferase in complex with a glutathione conjugate of 4-hydroxynon-2-enal in one subunit and glutathione in the other: evidence of signaling across the dimer interface.
Biochemistry, 38:11887-11894, 1999

PubMed Abstract: mGSTA4-4, a murine glutathione S-transferase (GST) exhibiting high activity in conjugating the lipid peroxidation product 4-hydroxynon-2-enal (4-HNE) with glutathione (GSH), was crystallized in complex with the GSH conjugate of 4-HNE (GS-Hna). The structure has been solved at 2.6 A resolution, which reveals that the active site of one subunit of the dimeric enzyme binds GS-Hna, whereas the other binds GSH. A marked asymmetry between the two subunits is evident. Most noticeable are the differences in the conformation of arginine residues 69 and 15. In all GST structures published previously, the guanidino groups of R69 residues from both subunits stack at the dimer interface and are related by a (pseudo-) 2-fold axis. In the present structure of mGSTA4-4, however, the two R69 side chains point in opposite directions, although their guanidino groups remain in contact. In the subunit with bound GSH, R69 also interacts with R15, and the guanidino group of R15 points away from the active site, whereas in the subunit that binds GS-Hna, R15 pivots into the active site, which breaks its interaction with R69. According to our previous results [Nanduri et al. (1997) Arch. Biochem. Biophys. 335, 305-310], the availability of R15 in the active site assists the conjugation of 4-HNE with GSH. We propose a model for the catalytic mechanism of mGSTA4-4 in conjugating 4-HNE with GSH-i.e., the guanidino group of R15 is available in the active site of only one subunit at any given time and the stacked pair of R69 residues act as a switch that couples the concerted movement of the two R15 side chains. The alternate occupancy of 4-HNE in the two subunits has been confirmed by our kinetic analysis that shows the negative cooperativity of mGSTA4-4 for 4-HNE. Disruption of the signaling between the subunits by mutating the R69 residues released the negative cooperativity with 4-HNE.

PubMed: 10508391
DOI: 10.1021/bi990468i

Experimental method

X-RAY DIFFRACTION (2.6 Å)