TAILIEUCHUNG - Báo cáo khoa học: Dimers of light-harvesting complex 2 from Rhodobacter sphaeroides characterized in reconstituted 2D crystals with atomic force microscopy

Microscopic and light spectroscopic investigations on the supramolecular architecture of bacterial photosynthetic membranes have revealed the pho-tosynthetic protein complexes to be arranged in a densely packed energy-transducing network. | ỊFEBS Journal Dimers of light-harvesting complex 2 from Rhodobacter sphaeroides characterized in reconstituted 2D crystals with atomic force microscopy Lu-Ning Liu1 2 Thijs J. Aartsma1 and Raoul N. Frese1 1 Huygens Laboratory Department of Biophysics Leiden University The Netherlands 2 State Key Lab of MicrobialTechnology Shandong University Jinan China Keywords 2D crystallization atomic force microscopy light-harvesting complex 2 polymorphism Rhodobacter sphaeroides Correspondence R. N. Frese Huygens Laboratory Biophysics Department Leiden University 2333CA Leiden The Netherlands Fax 31 0 71 527 5936 Tel 31 0 71 527 5970 E-mail frese@ Received 26 February 2008 revised 28 March 2008 accepted 16 April 2008 doi Microscopic and light spectroscopic investigations on the supramolecular architecture of bacterial photosynthetic membranes have revealed the photosynthetic protein complexes to be arranged in a densely packed energytransducing network. Protein packing may play a determining role in the formation of functional photosynthetic domains and membrane curvature. To further investigate in detail the packing effects of like-protein photosynthetic complexes we report an atomic force microscopy investigation on artificially created 2D crystals of the peripheral photosynthetic light-harvesting complexes 2 LH2 s from the bacterium Rhodobacter sphaeroides. Instead of the usually observed one or two different crystallization lattices for one specific preparation protocol we find seven different packing lattices. The most abundant crystal types all show a tilting of LH2. Most surprisingly although LH2 is a monomeric protein complex in vivo we find an LH2 dimer packing motif. We further characterize two different dimer configurations in type 1 the LH2 s are tilted inwards and in type 2 they are titlted outwards. Closer inspection of the lattices surrounding the LH2 dimers indicates their close resemblance to those LH2 s .

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