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A fresh look at the evolution and diversification of photochemical reaction centers.

Cardona T - Photosyn. Res. (2014)

Bottom Line: In this review, I reexamine the origin and diversification of photochemical reaction centers based on the known phylogenetic relations of the core subunits, and with the aid of sequence and structural alignments.Moreover, it becomes evident that the Acidobacteria and the Proteobacteria shared a more recent common phototrophic ancestor, and this is also likely for the Chloroflexi and the Cyanobacteria.The primordial phototrophic ancestor must have had both Type I and Type II reaction centers.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. t.cardona@imperial.ac.uk.

ABSTRACT
In this review, I reexamine the origin and diversification of photochemical reaction centers based on the known phylogenetic relations of the core subunits, and with the aid of sequence and structural alignments. I show, for example, that the protein folds at the C-terminus of the D1 and D2 subunits of Photosystem II, which are essential for the coordination of the water-oxidizing complex, were already in place in the most ancestral Type II reaction center subunit. I then evaluate the evolution of reaction centers in the context of the rise and expansion of the different groups of bacteria based on recent large-scale phylogenetic analyses. I find that the Heliobacteriaceae family of Firmicutes appears to be the earliest branching of the known groups of phototrophic bacteria; however, the origin of photochemical reaction centers and chlorophyll synthesis cannot be placed in this group. Moreover, it becomes evident that the Acidobacteria and the Proteobacteria shared a more recent common phototrophic ancestor, and this is also likely for the Chloroflexi and the Cyanobacteria. Finally, I argue that the discrepancies among the phylogenies of the reaction center proteins, chlorophyll synthesis enzymes, and the species tree of bacteria are best explained if both types of photochemical reaction centers evolved before the diversification of the known phyla of phototrophic bacteria. The primordial phototrophic ancestor must have had both Type I and Type II reaction centers.

No MeSH data available.


Related in: MedlinePlus

Evolutionary relationships of reaction center proteins as suggested by molecular phylogenies. At the beginning (bottom), the most ancestral photochemical reaction center protein was encoded by a single gene, this diverged giving rise to the precursor genes for the first Type II and Type I reaction center proteins. Initially both reaction centers were homodimeric. Type II reaction centers seem to have acquired heterodimericity by convergent evolution twice. Heterodimeric Type I reaction centers have only evolved once in the phylum Cyanobacteria
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Fig5: Evolutionary relationships of reaction center proteins as suggested by molecular phylogenies. At the beginning (bottom), the most ancestral photochemical reaction center protein was encoded by a single gene, this diverged giving rise to the precursor genes for the first Type II and Type I reaction center proteins. Initially both reaction centers were homodimeric. Type II reaction centers seem to have acquired heterodimericity by convergent evolution twice. Heterodimeric Type I reaction centers have only evolved once in the phylum Cyanobacteria

Mentions: In conclusion, the evolution of Type II reaction center subunits can be summarized in three major steps (Fig. 5). First, the gene encoding the only subunit for an ancestral homodimeric Type II reaction center protein diverged into two forms: one was the ancestor of all L and M subunits, and the other was the ancestor of all D1 and D2 (Beanland 1990; Blankenship 1992; Rutherford and Nitschke 1996). This could have been speciation as an ancestral bacterium evolved into two different forms or a gene duplication event. Second, the ancestral gene of D1 and D2 duplicated, and each copy diverged and specialized in an ancestor to the phylum Cyanobacteria. Similarly, the ancestral genes to L and M duplicated in an ancestral bacterium that likely preceded the origin of the Chloroflexi and the Proteobacteria. And third, as the Chloroflexi and the Proteobacteria finally diverged, so did L and M in each group.Fig. 5


A fresh look at the evolution and diversification of photochemical reaction centers.

Cardona T - Photosyn. Res. (2014)

Evolutionary relationships of reaction center proteins as suggested by molecular phylogenies. At the beginning (bottom), the most ancestral photochemical reaction center protein was encoded by a single gene, this diverged giving rise to the precursor genes for the first Type II and Type I reaction center proteins. Initially both reaction centers were homodimeric. Type II reaction centers seem to have acquired heterodimericity by convergent evolution twice. Heterodimeric Type I reaction centers have only evolved once in the phylum Cyanobacteria
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4582080&req=5

Fig5: Evolutionary relationships of reaction center proteins as suggested by molecular phylogenies. At the beginning (bottom), the most ancestral photochemical reaction center protein was encoded by a single gene, this diverged giving rise to the precursor genes for the first Type II and Type I reaction center proteins. Initially both reaction centers were homodimeric. Type II reaction centers seem to have acquired heterodimericity by convergent evolution twice. Heterodimeric Type I reaction centers have only evolved once in the phylum Cyanobacteria
Mentions: In conclusion, the evolution of Type II reaction center subunits can be summarized in three major steps (Fig. 5). First, the gene encoding the only subunit for an ancestral homodimeric Type II reaction center protein diverged into two forms: one was the ancestor of all L and M subunits, and the other was the ancestor of all D1 and D2 (Beanland 1990; Blankenship 1992; Rutherford and Nitschke 1996). This could have been speciation as an ancestral bacterium evolved into two different forms or a gene duplication event. Second, the ancestral gene of D1 and D2 duplicated, and each copy diverged and specialized in an ancestor to the phylum Cyanobacteria. Similarly, the ancestral genes to L and M duplicated in an ancestral bacterium that likely preceded the origin of the Chloroflexi and the Proteobacteria. And third, as the Chloroflexi and the Proteobacteria finally diverged, so did L and M in each group.Fig. 5

Bottom Line: In this review, I reexamine the origin and diversification of photochemical reaction centers based on the known phylogenetic relations of the core subunits, and with the aid of sequence and structural alignments.Moreover, it becomes evident that the Acidobacteria and the Proteobacteria shared a more recent common phototrophic ancestor, and this is also likely for the Chloroflexi and the Cyanobacteria.The primordial phototrophic ancestor must have had both Type I and Type II reaction centers.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. t.cardona@imperial.ac.uk.

ABSTRACT
In this review, I reexamine the origin and diversification of photochemical reaction centers based on the known phylogenetic relations of the core subunits, and with the aid of sequence and structural alignments. I show, for example, that the protein folds at the C-terminus of the D1 and D2 subunits of Photosystem II, which are essential for the coordination of the water-oxidizing complex, were already in place in the most ancestral Type II reaction center subunit. I then evaluate the evolution of reaction centers in the context of the rise and expansion of the different groups of bacteria based on recent large-scale phylogenetic analyses. I find that the Heliobacteriaceae family of Firmicutes appears to be the earliest branching of the known groups of phototrophic bacteria; however, the origin of photochemical reaction centers and chlorophyll synthesis cannot be placed in this group. Moreover, it becomes evident that the Acidobacteria and the Proteobacteria shared a more recent common phototrophic ancestor, and this is also likely for the Chloroflexi and the Cyanobacteria. Finally, I argue that the discrepancies among the phylogenies of the reaction center proteins, chlorophyll synthesis enzymes, and the species tree of bacteria are best explained if both types of photochemical reaction centers evolved before the diversification of the known phyla of phototrophic bacteria. The primordial phototrophic ancestor must have had both Type I and Type II reaction centers.

No MeSH data available.


Related in: MedlinePlus