PI: Hebert (KI)
Project: Electron crystallography of microsomal glutathione transferase
Two PhD students started in the group in March. Helena Olsson was financed from the SBNet but unfortunately she left for the pharmaceutical industry. Marika Joona took her position from Nov. 1, 1998.
The main objective of the project is to study the structure and function of microsomal glutathione transferase (MGST-1). This is a relatively small (monomer molecular weight 17.5 kD) membrane-bound enzyme which is important for detoxification in all types of organisms. Recently other proteins have been found which resembles MGST-1 in terms of hydropathy profile and it has been suggested that they all belong to a common family of membrane associated proteins in eicosanoid and glutathione metabolism.
We have demonstrated that MAPEG can form well ordered 2-D crystals which are suitable for structure analysis using cryo electron microscopy. Projection maps have been calculated at 3 Å resolution from two different crystal forms. Recently a 3D structure has been determined which reveals the fold of MGST-1.
Marika Joona and Helena Olsson have now shown that 2-D crystals of MGST-1 can be obtained under completely different conditions as compared to those used initially. Thus, crystals are obtained of glutathione free enzyme and a ternary intermediate dead-end complex. It will thus be possible to address questions concerning the location of binding sites and conformational changes. Moreover, a form of MGST-1 where glutathione has been replaced and inhibited by leukotriene C4 does also form 2-D crystals. It has also been demonstrated that the recombinant protein behaves similarly with respect to crystallisation. These results can be considered as important steps towards understanding the structure and function of MGST-1 in particular and the related proteins with a multitude of biological functions in general.
Latest update at 18 February, 1999.