Cyanobacteria genome

Molecular, spectroscopic, and functional genomics studies have demonstrated the remarkable similarity among the components of the photosynthetic machinery of cyanobacteria, algae, and plants. These organisms also share the need to balance the collection of energy for photosynthesis with the threat of photodestruction. Carotenoids are central to attaining this balance. 

The biological classification schemes for bacteria and archaea are still being developed because of the rapid pace of new discoveries in genomics. The two most important phyla of marine bacteria are the cyanobacteria, which are photosynthetic, and the proteobacteria. The latter include some photosynthetic species, such as the purple photosynthetic bacteria and N2 fixers. Other members of this diverse phylum are the methanotrophs, nitrifiers, hydrogen, sulfur and iron oxidizers, sulfete and sulfur reducers, and various bioluminescent species. 

As to the enzymes of PolyP metabolism in photosynthetic bacteria, polyphosphate kinase activity was revealed in the cyanobacteria Anacystis nidulans (Vaillancourt el al., 1978) and Oscillatoria redekei (Zaiss, 1985). The mutant in this enzyme had no PolyP granules observable by electron microscopy (Vaillancourt el al., 1978). The alignment analysis revealed the genes encoding putative polyphosphate kinase (ppkl and ppk.2) in several genomes of cyanobacteria (Zhang el al., 2002) (see Table 6.1 above). 

This would favour hypothesis II in Fig. 7.15. Even animals share some of the proteins (TDC, ODC, TyrDC, STS and CR). These observations indicate that the proteins very likely evolved in prokaryotes and were transferred into eucaryotes via either protobacteria (Fig. 7.18) or cyanobacteria, the progenitors of mitochondria or chloroplasts, respectively. A number of SM (e.g. many terpenoids, QAs, the piperidine alkaloid coniine) are produced completely or partly in chloroplasts and/or mitochondria (see Chapter 1). The corresponding genes are mostly nuclear today. It is tempting to speculate that these localizations are indirect indicators of a former bacterial origin of the corresponding pathways. The introduction of bacterial genomes into eukaryotes was... 

Genome sequencing also reveals other differences in utilization of nitrogen sources between cyanobacteria (see also Chapter 24, Scanlan and Post, this volume). 

Figure 5 The future of natural products. Salinosporamide comes from a new genus of marine actinomycetes, while jamaicamide A and curacin A are produced by cyanobacteria. ECO-02301 was discovered by mining a bacterial genome.

Ascidians are marine filter feeders with a rich natural products chemistry that five commonly associated with symbiotic bacteria (88, 89, 109). A well-studied symbiosis consists of photosynthetic Prochloron spp. cyanobacteria that occur in ascidians of the family Didemnidae (110). Prochloron spp. also can be found in bacterial mat structures of stromatoliths (111) but so far have not been detected outside of such structured environments. From didemnid ascidians, numerous cytotoxic cyclic peptides of the patellamide group (Fig. 5) were isolated (109, 112, 113). Mechanical separation of the Prochloron sp. symbiont from its host Lissoclinum patella and subsequent genome sequencing revealed a set of biosynthetic genes that after transfer into E. coli enabled this bacterium to produce two different patellamides (114). The genes also were identified in an independent study by screening a library of Prochloron sp. DNA... 

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