Peter Holm
PI: Hebert (KI)
Project: Electron crystallography of microsomal glutathione transferase
Funding ends: 30 June, 2002
Research project
Microsomal glutathione transferase 1 (MGST1) is a 53 kDa, membrane-bound detoxification enzyme. It conjugates glutathione to a variety of electrophilic compounds thereby made more hydrophilic thus accessible for further processing or excretion. Other characteristics of the protein, like its glutathione peroxidase activity and the noticeable expression levels in other tissues than the liver, may account for a general functional property in protecting organisms against lipid peroxidation and oxidative stress.
Under certain conditions MGST1 forms large, well-ordered 2-D crystals (Hebert et al., 1995). Two crystal forms are obtained, one orthorhombic and one hexagonal, under similar conditions (Schmidt-Krey et al., 1998) and the projection structures of the enzyme, calculated at 3 Å resolution, both of them are very similar (Hebert et al., 1997, Schmidt-Krey et al., 1999). Recently the 3-D structure was calculated to 6 Å resolution from hexagonal crystals (Schmidt-Krey et al., 2000).
In November 2001 our manuscript entitled "The 3-D Structure of Microsomal Glutathione Transferase 1 at 6 Å resolution as determined by electron crystallography of p22121 crystals" was accepted for publication in Biochimica et Biophysica Acta.
In addition to the completion of the manuscript, the emphasis of the year 2001 has been to further enhance the data set of the orthorhombic crystal form to be able to calculate a high-resolution 3-D structure of MGST1. This has involved continuous crystallisation trials followed by screening for crystals in the Philips CM-120 electron microscope at KI in Huddinge, Sweden. In October enough material had been obtained to allow data collection on the JEOL 3000SFF electron microscope in Professor Fujiyoshis group at Kyoto University, Japan. The goal of this trip was to learn the practical use of this state of the art microscope and to collect high-tilted data of the crystals. The journey was partly financed through a generous travel grant from SBNet.
During the year computer processing of images in both the data sets (p6 and p22121 crystals) has been done.
Publications
* PJ Holm, R Morgenstern & H Hebert (2002). The 3-D structure of microsomal glutathione transferase 1 at 6 Å resolution as determined by electron crystallography of p22121 crystals Biochim. Biophys. Acta, in press.
Conferences and workshops
* 52nd SCANDEM Meeting [June 12-15, 2001, Stockholm, Sweden] Poster presented.
* 5th Conference of the Swedish Structural Biology Network [June 15-18, 2001, Tällberg, Sweden] Poster presented.
* SWEGENE Workshop on Membrane Protein Purification and Crystallisation [October 8-9, 2001, Lund, Sweden] Oral presentation.
Courses
* Cryo-Electron Tomography on single proteins in solution [KI, Sweden, 1-5/10 2001]
* Core Course in General Science [KI, Sweden, 26/2-6/4 2001]
* Python Programming Introductory Course [KI, Sweden, 24-25/11 2001]
Teaching
* Laboratory practical supervisor of Physical Chemistry course on Södertörn University College. (Approximately 16 hours)
* Computer practical supervisor of the computer program CRISP on Södertörn University College. (Approximately 16 hours)
Miscellaneous
Member of the organising committee and responsible for biological abstracts for the Scandinavian Electron Microscopy Society Meeting [Stockholm, June 2001].
Latest update at 29 March, 2001.