PARENT SESSION
Posters P5A Type II reaction centres : Structure. Abstracts (289-312)

Localisation of phospholipids tightly bound to reaction centres from Rhodobacter sphaeroides: use of brominated lipids. Aleksander Roszak^*,1, Alastair Gardiner², Neil Isaacs¹, Richard Cogdell², ¹ Department of Chemistry, Glasgow, UK² Division of Biochemistry and Molecular Biology, IBLS, Glasgow, UK

ABSTRACT- Following the finding of tightly bound cardiolipin [McAuley, K. E. et al. (1999) Proc. Natl. Acad. Sci. U.S.A. 96, 14706] we have been interested to try to map the interactions between both, tightly bound phospholipids and detergent molecules, and the surface of the reaction centre (RC). It can be very difficult to distinguish between these two types of molecules. In order to overcome this problem we have crystallised the RCs from Rhodobacter sphaeroides in the presence of brominated derivatives of phosphocholine. The idea was to tag the phospholipid molecules with the heavy atoms which could be recognised in the electron density maps. These experiments proved to be successful. We will describe the structure of reaction centre and the localisation of the labelled phospholipids. This strategy may well be of general applicability for the study of protein-lipid interactions. Supported by grants from BBSRC and Wellcome Trust.

KEY WORDS: bound brominated phospholipids, protein-lipid interactions, bacterial photosynthetic reaction centre, bound detergent molecules