PI: Nordlund (SU)
Project: Structural studies on protein phosphatases
Agnes Rinaldo-Matthis, PhD student, on the SSF grant has been on maternity leave between November 97 and August 98. The work before and after this period has concerned two projects:
Co-crystallisation of antibody fragments with the membrane protein complex Photosystem II from Spinacia oleracea (spinach)
Photosystem II (PSII) is a membrane bound complex involved in photosynthesis. It contains a core formed by several transmembrane subunits and contain many different cofactors including the fascinating oxygen evolving manganese centre. Due to its complexity it is notoriously difficult to crystallise.
The basic strategy of this project is to use structure specific antibody fragments, selected using the phage display techniques, for 1) allowing the purification of homogeneous samples of photosystem II and 2) subsequently co-crystallise the antibody fragments together with the PSII complex.
We are in the process of making two different phage libraries. One derived from a rabbit immunised with a small peptide sequence from the D1 protein in PSII and one from mouse immunised with the whole core complex of PSII (This work is done in collaboration with Mats Persson, CMM, KS). Hopefully these libraries will be available for selection during the first half of 1999.
Expression, purification and structure determination of 5[[yen]]3(deoxy)-nucleotidase
5-3(deoxy)-nucleotidase preferentially dephosphorylates deoxyribonucleotides compared to ribonucleotides. The mouse gene was cloned (not yet published) in the laboratory of Vera Bianchi in Italy, University of Padova, and might have important functions in nucleotide metabolism. A R-M is working on obtaining good expression and purification protocols for this protein, to allow the production of crystals suitable for crystallographic studies. Presently several expression systems, as well as mutant proteins are screened for suitability.
Martin E Andersson, Martin Högbom, Agnes Rinalo-Matthis, Kristoffer K Andersson, Britt-Marie Sjöberg and Pär Nordlund, JACS, in press.