Split photosystem protein, linear-mapping topology, and growth of structural complexity in the plastid genome of Chromera velia

The canonical photosynthetic plastid genomes consist of a single circular-mapping chromosome that encodes a highly conserved protein core, involved in photosynthesis and ATP generation. Here, we demonstrate that the plastid genome of the photosynthetic relative of apicomplexans, Chromera velia, depa...

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Bibliographic Details
Published in:Molecular biology and evolution 2013-11, Vol.30 (11), p.2447-2462
Main Authors: Janouskovec, Jan, Sobotka, Roman, Lai, De-Hua, Flegontov, Pavel, Koník, Peter, Komenda, Josef, Ali, Shahjahan, Prásil, Ondrej, Pain, Arnab, Oborník, Miroslav, Lukes, Julius, Keeling, Patrick J
Format: Article
Language:English
Subjects:
Adenosine triphosphatase
Adenosine Triphosphate - metabolism
Alveolata - genetics
Amino acids
ATP Synthetase Complexes - chemistry
ATP Synthetase Complexes - genetics
ATP Synthetase Complexes - metabolism
Base Sequence
Chromosome Mapping
Chromosomes
Evolution, Molecular
Gene Expression Profiling
Genome, Protozoan
Genomes
Models, Molecular
Molecular Sequence Data
Multigene Family
Photosynthesis - genetics
Photosystem I Protein Complex - chemistry
Photosystem I Protein Complex - genetics
Photosystem I Protein Complex - metabolism
Plastids
Polymerase chain reaction
Protein Structure, Tertiary
Proteins
Protozoan Proteins - chemistry
Protozoan Proteins - genetics
Protozoan Proteins - metabolism
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Summary:The canonical photosynthetic plastid genomes consist of a single circular-mapping chromosome that encodes a highly conserved protein core, involved in photosynthesis and ATP generation. Here, we demonstrate that the plastid genome of the photosynthetic relative of apicomplexans, Chromera velia, departs from this view in several unique ways. Core photosynthesis proteins PsaA and AtpB have been broken into two fragments, which we show are independently transcribed, oligoU-tailed, translated, and assembled into functional photosystem I and ATP synthase complexes. Genome-wide transcription profiles support expression of many other highly modified proteins, including several that contain extensions amounting to hundreds of amino acids in length. Canonical gene clusters and operons have been fragmented and reshuffled into novel putative transcriptional units. Massive genomic coverage by paired-end reads, coupled with pulsed-field gel electrophoresis and polymerase chain reaction, consistently indicate that the C. velia plastid genome is linear-mapping, a unique state among all plastids. Abundant intragenomic duplication probably mediated by recombination can explain protein splits, extensions, and genome linearization and is perhaps the key driving force behind the many features that defy the conventional ways of plastid genome architecture and function.
ISSN:0737-4038
1537-1719
DOI:10.1093/molbev/mst144