Enigmatic Evolutionary History of Porphobilinogen Deaminase in Eukaryotic Phototrophs
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Biology Centre CAS, Institute of Parasitology, Branišovská 31, 370 05 České Budějovice, Czech Republic
2
Faculty of Science, University of South Bohemia, Branišovská 31, 370 05 České Budějovice, Czech Republic
Academic Editor: Andrés Moya
Biology 2021, 10(5), 386; https://doi.org/10.3390/biology10050386
Received: 25 March 2021
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Revised: 21 April 2021
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Accepted: 27 April 2021
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Published: 29 April 2021
(This article belongs to the Section Evolutionary Biology)
Simple Summary
The heme pathway is essential for most of cellular life. In eukaryotic phototrophs, the entire pathway is plastid localized. Despite that, the enzyme responsible for the synthesis of hydroxymethylbilane, porphobilinogen deaminase, shows α-proteobacterial instead of expected cyanobacterial origins in rhodophytes, chlorophytes, plants, and most algae with complex plastid. However, no such enzyme has been found in the supposed partners of plastid endosymbioses, the heterotrophic eukaryotes, and cyanobacteria. I propose two scenarios explaining this phenomenon by either endosymbiotic gene transfer from the ancestor of mitochondria or a non-endosymbiotic lateral gene transfer from unspecified α-proteobacterium. Phylogenetic analysis of porphobilinogen deaminases does not reject any of the two proposed evolutionary scenarios.
In most eukaryotic phototrophs, the entire heme synthesis is localized to the plastid, and enzymes of cyanobacterial origin dominate the pathway. Despite that, porphobilinogen deaminase (PBGD), the enzyme responsible for the synthesis of hydroxymethybilane in the plastid, shows phylogenetic affiliation to α-proteobacteria, the supposed ancestor of mitochondria. Surprisingly, no PBGD of such origin is found in the heme pathway of the supposed partners of the primary plastid endosymbiosis, a primarily heterotrophic eukaryote, and a cyanobacterium. It appears that α-proteobacterial PBGD is absent from glaucophytes but is present in rhodophytes, chlorophytes, plants, and most algae with complex plastids. This may suggest that in eukaryotic phototrophs, except for glaucophytes, either the gene from the mitochondrial ancestor was retained while the cyanobacterial and eukaryotic pseudoparalogs were lost in evolution, or the gene was acquired by non-endosymbiotic gene transfer from an unspecified α-proteobacterium and functionally replaced its cyanobacterial and eukaryotic counterparts.
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Keywords:
porphobilinogen deaminase; hydroxymethylbilane synthase; heme biosynthesis; evolution; mitochondrion; gene replacement; horizontal gene transfer
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MDPI and ACS Style
Oborník, M. Enigmatic Evolutionary History of Porphobilinogen Deaminase in Eukaryotic Phototrophs. Biology 2021, 10, 386. https://doi.org/10.3390/biology10050386
AMA Style
Oborník M. Enigmatic Evolutionary History of Porphobilinogen Deaminase in Eukaryotic Phototrophs. Biology. 2021; 10(5):386. https://doi.org/10.3390/biology10050386
Chicago/Turabian StyleOborník, Miroslav. 2021. "Enigmatic Evolutionary History of Porphobilinogen Deaminase in Eukaryotic Phototrophs" Biology 10, no. 5: 386. https://doi.org/10.3390/biology10050386
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