Interrelation between cyanophycin synthesis, L-arginine catabolism and photosynthesis in the cyanobacterium Synechocystis sp. strain PCC 6803.
Ultrastructural and immunocytochemical investigations gave evidence that cyanophycin (multi-L-arginyl-poly-L-aspartate) granules accumulate in the cyanobacterium Synechocystis sp. strain PCC 6803 under nutrient deficient growth conditions, especially under phosphate limitation. Besides nutrient deficiency, growth of Synechocystis PCC 6803 on L-arginine or L-asparagine as sole N-source also led to high increase of cyanophycin synthesis, while growth on the combination of L-arginine or L-asparagine with nitrate only caused minor cyanophycin accumulation. Growth of Synechocystis PCC 6803 on L-arginine as sole N-source caused substantial morphological and physiological changes, such as severe thylakoid membrane degradation with partial loss of pigments and photosynthetic activity leading to a phenotype almost like that seen under nutrient deficiency. In contrast to the wild type, the PsbO-free Synechocystis PCC 6803 mutant could grow on L-arginine as sole N-source with only minor morphological and physiological changes. Due to its fairly balanced growth, the mutant accumulated only few cyanophycin granules. L-arginine degrading activity (measured as ornithine and ammonium formation) was high in the PsbO-free mutant but not in the wild type when cells were grown on L-arginine as sole N-source. In both cells types the L-arginine degrading activity was high (although in the PsbO-free mutant about twice as high as in wild type), when cells were grown on L-arginine in combination with nitrate, and as expected very low when cells were grown on nitrate as sole N-source. Thus, net cyanophycin accumulation in Synechocystis PCC 6803 is regulated by the relative concentration of L-arginine to the total nitrogen pool, and the intracellular L-arginine concentration is greatly influenced by the activity of the L-arginine degrading enzyme system which in part is regulated by the activity status of photosystem II. These results suggest a complex interrelation between cyanophycin synthesis, L-arginine catabolism, and in addition photosynthesis in Synechocystis PCC 6803.
Stephan
D P
DP
Biologie 1: Morphologie der Pflanzen und Feinbau der Zelle, Universität Bielefeld, Germany.
Ruppel
H G
HG
Pistorius
E K
EK
D001120:Arginine / Q000378:metabolism*; D001216:Asparagine / Q000378:metabolism; D001426:Bacterial Proteins; D002734:Chlorophyll / Q000378:metabolism; D000458:Cyanobacteria / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000378:metabolism / Q000648:ultrastructure; D007700:Kinetics; D010788:Photosynthesis; D010798:Phycocyanin / Q000378:metabolism; D010940:Plant Proteins / Q000096:biosynthesis*
D001426:Bacterial Proteins; D010940:Plant Proteins; C002497:allophycocyanin; C024250:cyanophycin; D010798:Phycocyanin; D002734:Chlorophyll; D001216:Asparagine; D001120:Arginine