Synechocystis

A shift in temperature from 38 to 22 °C leads to desaturation of fatty acids in Anabaena variabilis [110], resulting in control of the fluidity of the plasma membrane. Mutants have been isolated in Synechocystis PCC 6803 that were defective in desaturation of fatty acids, and the growth rate of one of these mutants was much lower than that of the wild-type at 22 °C [112]. It turned out that the mutant strain had a mutation in the gene desA, and when the wild-type allele was introduced into the chilling-sensitive cyanobacterium Anacystis nidulans, it resulted in increasing the tolerance of that strain to low temperature [113]. These experiments nicely demonstrate the existence of a mechanism of adaptation to low temperature in a chilling-tolerant cyanobacterium. 

Isomerisation of 15-c/5-phytoene to the all-/ra x configuration must occur during the desaturation steps, since most desaturated carotenes are in the all-trans form. The CRTI type desaturases appear to be able to carry out this isomerisation themselves (Fraser et al, 1992 Bartley etal, 1999), but mutants of PDS/ZDS-type organisms accumulate cis isomers of unsaturated carotenes, suggesting the presence of a separate isomerase (Clough and Pattenden, 1983 Ernst and Sandmann, 1988). Three recent publications have reported the cloning of a carotene isomerase (CrtlSO) from tomato (Isaacson et al, 2002), Arabidopsis (Park et al, 2002) and Synechocystis 6803 (Breitenbach... 

Masamoto, K. et al.. Identification of a gene required for cis-to-trans carotene isomerization in carotenogenesis of the cyanobacterium Synechocystis sp. PCC 6803, Plant Cell Physiol. 42, 1398, 2001. 

Breitenbach, J., Vioque, A., and Sandmann, G., Gene sll0033 from Synechocystis 6803 encodes a carotene isomerase involved in the biosynthesis of aU-E lycopene,... 

Genes encoding glucose transporters have recently been cloned from three photosynthetic organisms, the prokaryotic cyanobacterium Synechocystis [208,209], the... 

E. coll Chlorella Arabidopsis Synechocystis Leishaania Neurospora qa-y E. coll paH322 E. coli CIT E. coli LacY... 

E. coli AraE E. coli XylE E. coli GelP Chlorella Arabidopsis Synechocystis Leishmania Neurospora qa-y e. coli pBRl22 E. coli CIT E. coli I CY... 

In contrast to the photosynthetic eukaryotes, photoprotection in cyanobacteria is not induced by the presence of a transthylakoid ApH or the excitation pressure on PSII. Instead, intense blue-green light (400-550 nm) induces a quenching of PSII fluorescence that is reversible in minutes even in the presence of translation inhibitors (El Bissati et al. 2000). Fluorescence spectra measurements and the study of the NPQ mechanism in phycobilisome- and PSII-mutants of the cyanobacterium Synechocystis PCC6803 indicate that this mechanism involves a specific decrease of the fluorescence emission of the phycobilisomes and a decrease of the energy transfer from the phycobilisomes to the RCs (Scott et al. 2006, Wilson et al. 2006). The site of the quenching appears to be the core of the phycobilisome (Scott et al. 2006, Wilson et al. 2006, Rakhimberdieva et al. 2007b). 

FIGURE 1.2 In situ localization of the OCP-green fluorescence protein (GFP) fusion protein Immunogold labeling of a thin section of OCP-GFP transformed Synechocystis PCC6803 OCP-GFP cells were labeled with a polyclonal antibody against the GFP coupled to 10 nm gold particles. Bar = 0.5 pm. 

El Bissati, K., E. Delphin, N. Murata, A. Etienne, and D. Kirilovsky (2000). Photosystem II fluorescence quenching in the cyanobacterium Synechocystis PCC 6803 Involvement of two different mechanisms. Biochim Biophys Acta 1457(3) 229-242. 

Fulda, S., S. Mikkat, F. Huang et al. (2006). Proteome analysis of salt stress response in the cyanobacterium Synechocystis sp. strain PCC 6803. Proteomics 6(9) 2733-2745. 

Kanesaki, Y., I. Suzuki, S. I. Allakverdiev, K. Mikami, and N. Murata (2002). Salt stress and hyperosmotic stress regulate the expression of different sets of genes in Synechocystis sp PCC6803. Biochem Biophys... 

Rakhimberdieva, M. G., Y. V. Bolychevtseva, I. V. Elanskaya, and N. V. Karapetyan (2007a). Protein-protein interactions in carotenoid triggered quenching of phycobilisome fluorescence in Synechocystis sp. PCC 6803. FEBS Lett 581(13) 2429-2433. 

Sato, S., Y. Shimoda, A. Murakiet al. (2007). A large-scale protein-protein interaction analysis in Synechocystis sp. PCC6803. DNA Res 14 207-216. 

Structural information about the oxygenases provided limited insight into the mechanism (Schmidt et al. 2006). The crystallized enzyme from Synechocystis sp. PCC6803 is membrane associated and the interaction with the membrane is believed to be mediated by a nonpolar patch on the surface of the enzyme. This hydrophobic patch is thought to provide the necessary access of the protein to the membrane-bound carotenoids. Following withdrawal from the membrane, the substrate moves through the hydrophobic tunnel toward the metal center. The substrate orients the... 

Ruch, S., P. Beyer et al. (2005). Retinal biosynthesis in eubacteria In vitro characterization of a novel carotenoid oxygenase from Synechocystis sp. PCC 6803. Mol. Microbiol. 55(4) 1015-1024. 

---