Photosynthetic prokaryotes

H. Utkilen, in Photosynthetic Prokaryotes, ed. N. H. Mann and N. G. Carr, Plenum Press, New... 

Prokaryotic cells have only a single membrane, the plasma membrane or cell membrane. Because they have no other membranes, prokaryotic cells contain no nucleus or organelles. Nevertheless, they possess a distinct nuclear area where a single circular chromosome is localized, and some have an internal membranous structure called a mesosome that is derived from and continuous with the cell membrane. Reactions of cellular respiration are localized on these membranes. In photosynthetic prokaryotes such as the cyanobacteria,... 

Nultsch W, Hader D-P (1980) Light Perception and Sensory Transduction in Photosynthetic Prokaryotes. 41 111-139 Nyholm RS, see Hall DI (1973) 15 3-51... 

Several methylated sugars have been identified in hydrolyzates of LPS, cell-wall polysaccharides, and extracellular polysaccharides. A considerable number of these have been found in the LPS from photosynthetic prokaryotes. Two polysaccharides from Mycobacterium species, a glucan" and a mannan" are remarkable in that they contain high percentages of methylated sugars. Glycolipids from Mycobacterium species are also rich in methylated sugars, some of which have not been found elsewhere, but this is beyond the scope of the present article. 

Abbreviations LPS, lipopolysaccharide EPS, extracellular polysaccharide Photosynth., photosynthetic prokaryote. 

The oxidation of carotenes results in the formation of a diverse array of xanthophylls (Fig. 13.7). Zeaxanthin is synthesised from P-carotene by the hydroxylation of C-3 and C-3 of the P-rings via the mono-hydroxylated intermediate P-cryptoxanthin, a process requiring molecular oxygen in a mixed-function oxidase reaction. The gene encoding P-carotene hydroxylase (crtZ) has been cloned from a number of non-photosynthetic prokaryotes (reviewed by Armstrong, 1994) and from Arabidopsis (Sun et al, 1996). Zeaxanthin is converted to violaxanthin by zeaxanthin epoxidase which epoxidises both P-rings of zeaxanthin at the 5,6 positions (Fig. 13.7). The... 

Armstrong, G.A., Alberti, M., and Hearst, J.E., Conserved enzymes mediate the early reactions of carotenoid biosynthesis in nonphotosynthetic and photosynthetic prokaryotes, Proc. Natl. Acad. Sci. USA 87, 9975, 1990. 

This article elucidates molecular mechanisms in light perception, stimulus transformation and signal transmission in photosynthetic prokaryotes. Special emphasis is put on the distinction between various coupling between different light responses and photosynthesis. 

Photosynthetic prokaryotes do not have chloroplasts. Their photosynthetic pigments are embedded in their cell walls. Some use bacteriochlorophyll for light harvesting. In the proteobacteria and archaea, light harvesting is accomplished by the protein rhodopsin, which acts as a photo-driven proton pump that fuels phosphorylation of ADP. 

Cyanobacteria are photosynthetic prokaryotes that are widely distributed throughout marine and terrestrial environments. Members of the marine cyanobacteria genus Lyngbya are known to produce structurally interesting and biologically active secondary metabolites. Typically, linear/cyclic peptides and depsipeptides that include various nonproteinogenic amino acids are the major groups of these metabolites (Fig. 10.11), which can exhibit potent cytotoxicity. 

FIGURE 15.7 Phylogenetic distribution of MAAs by percent occurrence in individual species within algal (this category includes photosynthetic prokaryotic taxa indicated in Table 15.2), invertebrate, and chordate groups (see Table 15.2 for reference citations and groups included in these categories X = percent values for all taxa and all MAAs combined). 

V.E.,4,Russo, P.Galland Sensory Physiology of Phycomycesblakesleeanus(94 ref.) l4(Nultsch, D.-P.Hdder Light Perception and Sensory Transduction in Photosynthetic Prokaryotes (139 ref.)... 

Cyanobacteria are 02-evolving photosynthetic prokaryotes, many of which are able to fix atmospheric N2 via an ATP-dependent nitrogenase activity. The nitrogenase enzyme is oxygen-sensitive however, it is localized in specialized cells called heterocysts which lack PSII and has an envelope impermeable to 02. Under normal physiological conditions, the nitrogen fixed in the cells as ammonia is rapidly transformed to... 

Recent advances in understanding the phylogeny of photosynthetic prokaryotes have been made by comparing oligonucleotides derived from 16S rRNA [1]. Results of these analyses have renewed general interest in the comparative biochemistry of photosynthetic bacteria, since it is now clear that they are closely related to many non-photosynthetic bacteria. Extensive phylogenetic analysis has indicated that the ancestry of most, if not all, eubacteria and even the ancestry of the cellular organelles of eukaryotes, the mitochondria and chloroplasts, lies deeply entrenched in the history of the photosynthetic bacteria. 

Fig. 1. Dendrogram of relationships among photosynthetic prokaryotes and their relatives, after Stackebrandt and Woese [2], Five bacterial phyla [1] containing photosynthetic members are shown. The exact relationship of Heliobacterium chlorum to the gram-positive bacteria is not yet known. Not shown are the other five phyla without known photosynthetic-members peptidoglycan-less bacteria bacteroids, cytophagas and flavobacteria spirochaetes and leptospiras bdellovibrios, myxococci, and certain S and SOj reducers and Deinococcus. PS = photosynthetic for further explanation, see text.

Brune, D.C. and Triiper. H.G. (1985) Abstr., V. International Symposium on Photosynthetic Prokaryotes. Grindelwald, Switzerland, p. 237. 

Zuber, H. (1983) in Photosynthetic Prokaryotes Cell Differentiation and Function (Papageor-giou, G.C. and Packer. L.. cds.) pp. 23-42, Elsevier, Amsterdam. 

Partensky, F., Hess, W., and Vaulot, D. (1999). Prochlorococcus, a marine photosynthetic prokaryote of global significance. Microbiol. Mol. Biol. Rev. 63, 106—127. 

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