Structure-Function Studies of the Photosystem Ⅱ Extrinsic Subunits PsbQ and PsbP from the Cyanobacterium Synechocystis sp. PCC 6803
The oxygen-evolving centre of Photosystem Ⅱ (PS Ⅱ) is located on the lumenal side of the PS Ⅱ complex and is surrounded by a group of polypeptides known as the extrinsic proteins. In PS Ⅱ of the cyanobacterium Synechocystis sp. PCC 6803 six extrinsic proteins have been identified: PsbO, PsbP, PsbQ, PsbU, PsbV and Psb27. We have obtained two Xray crystallographic structures of PsbQ, from crystals grown in either the presence or absence of Zn2+ ions. The structures were solved by multiple wavelength anomalous dispersion phasing using data obtained from a selenomethionine derivative and have essentially identical structures. The protein was found to consist of a four-helix bundle with an updown-up-down fold. His76 (present in a unique HisGlyPro motif which forms a kink in helix 2 of cyanobacterial PsbQ) together with Asp116 (helix 3), coordinates Zn adjacent to a hydrophobic cavity on the H2/H3 face. We hypothesize this metal binding site and cavity may play a role in a protein-protein interaction with another PS Ⅱ subunit. Similar structure-function studies are underway for the PsbP subunit; to facilitate solving the structure of PsbP in solution we have determined the NMR backbone chemical shift values of isotopically labelled recombinant PsbP.
CyanoP CyanoQ Extrinsic Proteins Photosystem Ⅱ PsbP PsbQ Synechocystis
Simon A Jackson Robert D Fagerlund Mark G Hinds Sigurd M Wilbanks Julian J Eaton-Rye
Department of Biochemistry, University of Otago, New Zealand Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Australia
国际会议
15th International Conference on Photosynthesis(第15届国际光合作用大会)
北京
英文
86-90
2010-08-22（万方平台首次上网日期，不代表论文的发表时间）