Mutations of basic arginine residue 334 in the D1 protein of Photosystem II lead to unusual S2 state properties in Synechocystis sp. PCC 6803 |
| |
Authors: | Zhaoliang Li Robert L Burnap |
| |
Institution: | (1) Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA |
| |
Abstract: | The C-terminus region of the D1 protein of Photosystem II (PS II) is situated on the lumenal side of the complex and is likely
to be involved in the coordination of the active site Mn atoms of the water oxidation complex (WOC). The strictly conserved
arginine at position 334 (D1-334) was targeted for site-directed mutagenesis to explore the hypothesis that it is involved
in the PS II extrinsic protein binding, chloride binding, or proton transfer. Although it was found that D1-R334 probably
not essential for these functions, mutations at this position were found to uniquely alter the kinetics of S-state cycling
in general and the properties of the S2 state in particular. Substitutions of a glutamate (D1-R334E) and a valine (D1-R334V) for D1-R334 lead to an unusually stable
(t
1/2 >30 min at room temp) S2 state, but not S3, as measured by double flash measurements on the bare platinum electrode. However, measurements of fluorescence decay in
the presence of DCMU suggest the S2 state is only modestly affected by the mutations. Possible reasons for these apparently contradictory results are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. |
| |
Keywords: | photosynthesis manganese oxygen evolution S state decay Photosystem II psbA gene |
本文献已被 PubMed SpringerLink 等数据库收录! |
|