Purification, characterisation and crystallisation of photosystem II from Thermosynechococcus elongatus cultivated in a new type of photobioreactor.

The thermophilic cyanobacterium Thermosynechococcus elongatus was cultivated under controlled growth conditions using a new type of photobioreactor, allowing us to optimise growth conditions and the biomass yield. A fast large-scale purification method for monomeric and dimeric photosystem II (PSII) solubilized from thylakoid membranes of this cyanobacterium was developed using fast protein liquid chromatography (FPLC). The obtained PSII core complexes (PSIIcc) were analysed for their pigment stoichiometry, photochemical and oxygen evolution activities, as well as lipid and detergent composition. Thirty-six chlorophyll a (Chla), 2 pheophytin a (Pheoa), 9+/- 1 beta-carotene (Car), 2.9+/-0.8 plastoquinone 9 (PQ9) and 3.8+/-0.5 Mn were found per active centre. For the monomeric and dimeric PSIIcc, 18 and 20 lipid as well as 145 and 220 detergent molecules were found in the detergent shell, respectively. The monomeric and dimeric complexes showed high oxygen evolution activity with 1/4 O(2) released per 37-38 Chla and flash in the best cases. Crystals were obtained from dimeric PSIIcc by a micro-batch method. They diffract synchrotron X-rays to a maximum resolution of 2.9-A, resulting in complete data sets of 3.2 A resolution.

Crystallization and preliminary x-ray structure determination of Lupinus luteus PR10 protein.

The pathogenesis-related protein of the PR10 class from Lupinus luteus (yellow lupin), LlPR10.1A, is constitutively expressed in roots. It is also accumulated in leaves treated with a suspension of pathogenic bacteria as a response to stress. Recombinant yellow-lupin LlPR10.1A protein has been overexpressed in Escherichia coli as a fusion product with maltose-binding protein. LlPR10.1A crystallizes in the orthorhombic P2(1)2(1)2(1) space group and the crystals diffract to 2.45 A resolution. The structure has been solved by molecular replacement, using the structure of a birch-pollen allergen protein as a model.