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Novel folding and stability defects cause a deficiency of human glutathione transferase omega 1

Journal Article


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Abstract


  • The polymorphic deletion of Glu-155 from human glutathione transferase omega1 (GSTO1-1) occurs in most populations. Although the recombinant ΔGlu-155 enzyme expressed in Escherichia coli is active, the deletion causes a deficiency of the active enzyme in vivo. The crystal structure and the folding/unfolding kinetics of the ΔGlu-155 variant were determined in order to investigate the cause of the rapid loss of the enzyme in human cells. The crystal structure revealed altered packing around the Glu-155 deletion, an increase in the predicted solvent-accessible area and a corresponding reduction in the buried surface area. This increase in solvent accessibility was consistent with an elevated Stern-Volmer constant. The unfolding of both the wild type and ΔGlu-155 enzyme in urea is best described by a three-state model, and there is evidence for the more pronounced population of an intermediate state by the ΔGlu-155 enzymes. Studies using intrinsic fluorescence revealed a free energy change around 14.4 kcal/mol for the wild type compared with around 8.6 kcal/mol for the ΔGlu-155 variant, which indicates a decrease in stability associated with the Glu-155 deletion. Urea induced unfolding of the wild type GSTO1-1 was reversible through an initial fast phase followed by a second slow phase. In contrast, the ΔGlu-155 variant lacks the slow phase, indicating a refolding defect. It is possible that in some conditions in vivo, the increased solvent-accessible area and the low stability of the ΔGlu-155 variant may promote its unfolding, whereas the refolding defect limits its refolding, resulting in GSTO1-1 deficiency.

Authors


  •   Zhou, Huina (external author)
  •   Brock, Joseph (external author)
  •   Casarotto, Marco G. (external author)
  •   Oakley, Aaron J.
  •   Board, Philip G. (external author)

Publication Date


  • 2011

Citation


  • Zhou, H., Brock, J., Casarotto, M. G., Oakley, A. J. & Board, P. G. (2011). Novel folding and stability defects cause a deficiency of human glutathione transferase omega 1. Journal of Biological Chemistry, 286 (6), 4271-4279.

Scopus Eid


  • 2-s2.0-79953013632

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2122&context=scipapers

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/1056

Number Of Pages


  • 8

Start Page


  • 4271

End Page


  • 4279

Volume


  • 286

Issue


  • 6

Place Of Publication


  • http://www.jbc.org/

Abstract


  • The polymorphic deletion of Glu-155 from human glutathione transferase omega1 (GSTO1-1) occurs in most populations. Although the recombinant ΔGlu-155 enzyme expressed in Escherichia coli is active, the deletion causes a deficiency of the active enzyme in vivo. The crystal structure and the folding/unfolding kinetics of the ΔGlu-155 variant were determined in order to investigate the cause of the rapid loss of the enzyme in human cells. The crystal structure revealed altered packing around the Glu-155 deletion, an increase in the predicted solvent-accessible area and a corresponding reduction in the buried surface area. This increase in solvent accessibility was consistent with an elevated Stern-Volmer constant. The unfolding of both the wild type and ΔGlu-155 enzyme in urea is best described by a three-state model, and there is evidence for the more pronounced population of an intermediate state by the ΔGlu-155 enzymes. Studies using intrinsic fluorescence revealed a free energy change around 14.4 kcal/mol for the wild type compared with around 8.6 kcal/mol for the ΔGlu-155 variant, which indicates a decrease in stability associated with the Glu-155 deletion. Urea induced unfolding of the wild type GSTO1-1 was reversible through an initial fast phase followed by a second slow phase. In contrast, the ΔGlu-155 variant lacks the slow phase, indicating a refolding defect. It is possible that in some conditions in vivo, the increased solvent-accessible area and the low stability of the ΔGlu-155 variant may promote its unfolding, whereas the refolding defect limits its refolding, resulting in GSTO1-1 deficiency.

Authors


  •   Zhou, Huina (external author)
  •   Brock, Joseph (external author)
  •   Casarotto, Marco G. (external author)
  •   Oakley, Aaron J.
  •   Board, Philip G. (external author)

Publication Date


  • 2011

Citation


  • Zhou, H., Brock, J., Casarotto, M. G., Oakley, A. J. & Board, P. G. (2011). Novel folding and stability defects cause a deficiency of human glutathione transferase omega 1. Journal of Biological Chemistry, 286 (6), 4271-4279.

Scopus Eid


  • 2-s2.0-79953013632

Ro Full-text Url


  • http://ro.uow.edu.au/cgi/viewcontent.cgi?article=2122&context=scipapers

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/1056

Number Of Pages


  • 8

Start Page


  • 4271

End Page


  • 4279

Volume


  • 286

Issue


  • 6

Place Of Publication


  • http://www.jbc.org/