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Photosynthesis evolution in Cyanobacteria
How and when Cyanobacteria evolved the ability to produce oxygen through photosynthesis is poorly understood. Soo et al. examined the genomes of Cyanobacteria and other related bacterial lineages. The phylogenetic relationships of these prokaryotes suggest that the evolution of aerobic respiration likely occurred multiple times. This, along with evidence that the modern photosynthetic system apparently arose through the lateral gene transfer and fusion of two photosynthetic systems, supports a relatively late origin of photosynthesis in evolutionary history.
Science, this issue p. 1436
The origin of oxygenic photosynthesis in Cyanobacteria led to the rise of oxygen on Earth ~2.3 billion years ago, profoundly altering the course of evolution by facilitating the development of aerobic respiration and complex multicellular life. Here we report the genomes of 41 uncultured organisms related to the photosynthetic Cyanobacteria (class Oxyphotobacteria), including members of the class Melainabacteria and a new class of Cyanobacteria (class Sericytochromatia) that is basal to the Melainabacteria and Oxyphotobacteria. All members of the Melainabacteria and Sericytochromatia lack photosynthetic machinery, indicating that phototrophy was not an ancestral feature of the Cyanobacteria and that Oxyphotobacteria acquired the genes for photosynthesis relatively late in cyanobacterial evolution. We show that all three classes independently acquired aerobic respiratory complexes, supporting the hypothesis that aerobic respiration evolved after oxygenic photosynthesis.