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Prokaryotic photosynthesis and phototrophy illuminated

2006; Elsevier BV; Volume: 14; Issue: 11 Linguagem: Inglês

10.1016/j.tim.2006.09.001

1878-4380

Donald A. Bryant, Niels‐Ulrik Frigaard,

Photoreceptor and optogenetics research

Genome sequencing projects are revealing new information about the distribution and evolution of photosynthesis and phototrophy. Although coverage of the five phyla containing photosynthetic prokaryotes (Chlorobi, Chloroflexi, Cyanobacteria, Proteobacteria and Firmicutes) is limited and uneven, genome sequences are (or soon will be) available for >100 strains from these phyla. Present knowledge of photosynthesis is almost exclusively based on data derived from cultivated species but metagenomic studies can reveal new organisms with novel combinations of photosynthetic and phototrophic components that have not yet been described. Metagenomics has already shown how the relatively simple phototrophy based upon rhodopsins has spread laterally throughout Archaea, Bacteria and eukaryotes. In this review, we present examples that reflect recent advances in phototroph biology as a result of insights from genome and metagenome sequencing. Genome sequencing projects are revealing new information about the distribution and evolution of photosynthesis and phototrophy. Although coverage of the five phyla containing photosynthetic prokaryotes (Chlorobi, Chloroflexi, Cyanobacteria, Proteobacteria and Firmicutes) is limited and uneven, genome sequences are (or soon will be) available for >100 strains from these phyla. Present knowledge of photosynthesis is almost exclusively based on data derived from cultivated species but metagenomic studies can reveal new organisms with novel combinations of photosynthetic and phototrophic components that have not yet been described. Metagenomics has already shown how the relatively simple phototrophy based upon rhodopsins has spread laterally throughout Archaea, Bacteria and eukaryotes. In this review, we present examples that reflect recent advances in phototroph biology as a result of insights from genome and metagenome sequencing. photosynthesis performed by organisms that do not evolve oxygen; it uses electron donors other than water for carbon dioxide reduction. a rhodopsin first identified in haloarchaea; translocates protons to the periplasm after light-induced isomerization of retinal. bacterial phylum that includes the green-colored and brown-colored green sulfur bacteria; these bacteria have type 1 reaction centers (containing BChl a and Chl a) and chlorosomes containing BChl c, d or e. They fix carbon by the reverse tricarboxylic cycle and oxidize sulfide, sulfur, thiosulfate, Fe2+ or H2. bacterial phylum that includes the filamentous anoxygenic phototrophs (FAPs), formerly known as the green gliding or green filamentous bacteria. bacterial phylum that includes all oxygen-evolving photosynthetic bacteria; they have Chl a-containing type 1 and type 2 reaction centers and fix carbon by the reductive pentose-phosphate (Calvin–Benson–Bassham) cycle; most have phycobilisomes as light-harvesting antennae (but see Prochlorophytes). Chloroflexi that have BChl a-containing, type 2 reaction centers. They might have chlorosomes that contain BChl c and most fix carbon by the 3-hydroxypropionate cycle whereas some oxidize sulfide or H2. endospore-producing photoheterotrophic bacteria of the phylum Firmicutes that have type 1 reaction centers and BChl g. photosynthesis that uses water as the electron donor and leads to oxygen evolution. a multisubunit protein complex containing chlorophylls or bacteriochlorophylls, in which light energy is transduced into redox chemistry. the reduction of carbon dioxide into biomass using energy derived from light. a metabolic mode in which organisms convert light energy into chemical energy for growth. a cyanobacterium such as Prochlorococcus spp. that synthesizes both divinyl-Chl a and divinyl-Chl b but lacks phycobilisomes. a rhodopsin first identified in marine proteobacteria, which translocates protons to the periplasm after light-induced isomerization of retinal. bacteria of the phylum Proteobacteria that produce BChl a or b under oxic or anoxic conditions. They have type 2 reaction centers and membrane-intrinsic caroteno-BChl antennae; many oxidize sulfide, thiosulfate, or H2 and they fix carbon by the reductive pentose-phosphate (Calvin–Benson–Bassham) cycle. a membrane-intrinsic protein characterized by seven transmembrane α-helices and a covalently attached carotenoid, retinal. RC family found in cyanobacteria, green sulfur bacteria and heliobacteria. They have either homodimeric or heterodimeric cores with [4Fe-4S] clusters as their terminal electron acceptors and produce weak oxidants and strong reductants (reduced ferredoxin). RC family found in cyanobacteria, purple bacteria and filamentous anoxygenic bacteria; all have heterodimeric cores with quinones as terminal electron acceptors. They produce strong oxidants and weak reductants (hydroquinone).