Toward the Crystallization of Photosystem II Core Complex from Pisum sativum L.

The crystallization of the higher plant ∼1 gigadalton homodimeric lipid-pigment−protein complex of photosystem II constitutes a challenging undertaking that has not been crowned with success to date. In the continuation of our previous efforts (Kuta-Smatanova et al. Photosyn. Res. 2006, 90, 255−259) that had provided needle and plate crystals of plant photosystem II for the first time, we report on a study to crystallize three-dimensional crystals of the photosystem II from Pisum sativum L. suitable for X-ray analysis. In our screening, we optimized temperature, supersaturation rate, and concentrations of detergents, buffers, salts, and organic additives. We used a sitting and hanging drop vapor-diffusion method, microbatch under oil and counter-diffusion techniques, and direct and cross-influenced procedures. We have identified that the major limiting factors for the growth of crystals are the photosystem II stability and requirement of indispensable divalent cations. The newly proposed physicochemical c...