PratA, a periplasmic tetratricopeptide repeat protein involved in biogenesis of photosystem II in Synechocystis sp. PCC 6803.
The light reactions of oxygenic photosynthesis are mediated by multisubunit pigment-protein complexes situated within the specialized thylakoid membrane system. The biogenesis of these complexes is regulated by transacting factors that affect the expression of the respective subunit genes and/or the assembly of their products. Here we report on the analysis of the PratA gene from the cyanobacterium Synechocystis sp. PCC 6803 that encodes a periplasmic tetratricopeptide repeat protein of formerly unknown function. Targeted inactivation of PratA resulted in drastically reduced photosystem II (PSII) content. Protein pulse labeling experiments of PSII subunits indicated that the C-terminal processing of the precursor of the reaction center protein D1 is compromised in the pratA mutant. Moreover, a direct interaction of PratA and precursor D1 was demonstrated by applying yeast two-hybrid analyses. This suggests that PratA represents a factor facilitating D1 maturation via the endoprotease CtpA. The periplasmic localization of PratA supports a model that predicts the initial steps of PSII biogenesis to occur at the plasma membrane of cyanobacterial cells.
Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, Germany.
Birgit
B
Klinkert
Friedrich
F
Ossenbühl
Martha
M
Sikorski
Stefan
S
Berry
Lutz
L
Eichacker
Jörg
J
Nickelsen
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D002734:Chlorophyll / Q000737:chemistry / Q000378:metabolism; D000458:Cyanobacteria / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D008027:Light; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D033903:Periplasmic Proteins / Q000737:chemistry / Q000378:metabolism*; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence; D046939:Synechocystis / Q000378:metabolism; D013696:Temperature; D020524:Thylakoids / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D033903:Periplasmic Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D010100:Oxygen