Interrelation between Cyanophycin Synthesis, L-Arginine Catabolism and Photosynthesis in the Cyanobacterium Synechocystis Sp. Strain PCC 6803

Abstract

L-Arginine C atabolism , Cyanophycin, U ltrastru ctu ral Analysis U ltrastru ctural and im m unocytochem ical investigations gave evidence th at cyanophycin (m ulti-L-arginyl-poly-L-aspartate) granules accum ulate in the cy anobacterium Synechocystis sp. strain PCC 6803 under n u trien t deficient grow th conditions, especially u n d e r phosphate lim itation. Besides nu trient deficiency, grow th o f Synechocystis PC C 6803 on L-arginine or lasparagine as sole N -source also led to high increase of cyanophycin synthesis, while grow th on the com bination of L-arginine or L-asparagine w ith nitrate only caused m inor cyanophycin accum ulation. G row th of Synechocystis PC C 6803 on L-arginine as sole N -source caused substantial m orphological and physiological changes, such as severe thylakoid m em brane degradation with partial loss of pigm ents and photo sy nth etic activity leading to a phenotype alm ost like th at seen under n u trien t deficiency. In con trast to the wild type, th e PsbO -free Synechocystis PC C 6803 m utant could grow on L-arginine as sole N -source w ith only m inor m orphological and physiological changes. D ue to its fairly balanced grow th, the m u tan t accu m ulated only few cyanophycin granules. L-arginine degrading activity (m easured as ornithine and am m onium form ation) was high in the P sbO -free m u tan t b u t n o t in the wild type when cells w ere grown on L-arginine as sole N -source. In b oth cells types the L-arginine degrading activity was high (although in the P sbO -free m u ta n t abo u t twice as high as in wild type), w hen cells were grown on L-arginine in co m bination with nitrate, and as ex p ected very low w hen cells were grown on n itrate as sole N -source. Thus, n et cyanophycin accum ulation in Synechocystis PCC 6803 is reg u lated by the relative co n cen tratio n o f L-arginine to the total nitrogen pool, and the intracellular L-arginine concen tratio n is greatly influenced by the activity of the L-arginine degrading enzym e system which in p a rt is reg u lated by the activity status of photosystem II. These results suggest a com plex in terre latio n b etw een cyanophycin synthesis, L-arginine catabolism , and in addition photosynthesis in Synechocystis PC C 6803.

Functional characterisation of the peroxiredoxin gene family members of Synechococcus elongatus PCC 7942

“…elongatus PCC 7942 was originally obtained from the Pasteur Culture Collection (Paris, France) and maintained in the collection of the institute. Cells were cultivated in 250 ml gas wash-bottles containing BG11 medium and aerated with air enriched in 2% CO 2 at 30°C (Stephan et al 2000). The medium was inoculated with cells at an optical density of OD 750 nm = 0.35.…”

Anaerobic and Aerobic Degradation of Cyanophycin by the Denitrifying Bacterium Pseudomonas alcaligenes Strain DIP1 and Role of Three Other Coisolates in a Mixed Bacterial Consortium

“…CGP accumulation is promoted by several conditions, including phosphorus limitation (46), sulfur limitation (5), low temperature, low light intensity, or a combination of these factors (32), and in the presence of translational or transcriptional inhibitors (3,13). CGP functions as a temporary nitrogen, energy, and possibly carbon reserve (12,26).…”

P II -Regulated Arginine Synthesis Controls Accumulation of Cyanophycin in Synechocystis sp. Strain PCC 6803

“…The amount of cyanophycin in cyanobacteria varies considerably with growth conditions. Its content is usually less than 1% of dry weight in rapidly growing cultures but is high (up to 18%) in stationaryphase cultures and under conditions of unbalanced growth such as sulfate or phosphate limitation (6,30,40,45). When nitrogenstarved cyanobacterial cultures were provided with combined nitrogen sources, a rapid but transient accumulation of cyanophycin occurred (3).…”