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Characterization and Evolution of Tetrameric Photosystem I from the Thermophilic Cyanobacterium Chroococcidiopsis sp TS-821
- Source :
- Plant Cell, 26(3), 1230-1245
- Publication Year :
- 2014
-
Abstract
- Photosystem I (PSI) is a reaction center associated with oxygenic photosynthesis. Unlike the monomeric reaction centers in green and purple bacteria, PSI forms trimeric complexes in most cyanobacteria with a 3-fold rotational symmetry that is primarily stabilized via adjacent PsaL subunits; however, in plants/algae, PSI is monomeric. In this study, we discovered a tetrameric form of PSI in the thermophilic cyanobacterium Chroococcidiopsis sp TS-821 (TS-821). In TS-821, PSI forms tetrameric and dimeric species. We investigated these species by Blue Native PAGE, Suc density gradient centrifugation, 77K fluorescence, circular dichroism, and single-particle analysis. Transmission electron microscopy analysis of native membranes confirms the presence of the tetrameric PSI structure prior to detergent solubilization. To investigate why TS-821 forms tetramers instead of trimers, we cloned and analyzed its psaL gene. Interestingly, this gene product contains a short insert between the second and third predicted transmembrane helices. Phylogenetic analysis based on PsaL protein sequences shows that TS-821 is closely related to heterocyst-forming cyanobacteria, some of which also have a tetrameric form of PSI. These results are discussed in light of chloroplast evolution, and we propose that PSI evolved stepwise from a trimeric form to tetrameric oligomer en route to becoming monomeric in plants/algae.
- Subjects :
- Cyanobacteria
Photosynthetic reaction centre
STRUCTURAL-CHARACTERIZATION
Circular dichroism
SP PCC 6803
Stereochemistry
Molecular Sequence Data
Plant Science
Biology
Photosynthesis
Photosystem I
Purple bacteria
PROTEIN COMPLEXES
Biopolymers
Microscopy, Electron, Transmission
RED ANTENNA STATES
SYNECHOCYSTIS SP
Amino Acid Sequence
Chroococcidiopsis
Research Articles
3-DIMENSIONAL STRUCTURE
Photosystem I Protein Complex
Sequence Homology, Amino Acid
Circular Dichroism
Cell Biology
biology.organism_classification
Native Polyacrylamide Gel Electrophoresis
Chloroplast
Biochemistry
ELECTRON CRYSTALLOGRAPHY
TARGETED INACTIVATION
SYNECHOCOCCUS SP
SUPRAMOLECULAR ORGANIZATION
Subjects
Details
- Language :
- English
- ISSN :
- 10404651
- Volume :
- 26
- Issue :
- 3
- Database :
- OpenAIRE
- Journal :
- Plant Cell
- Accession number :
- edsair.doi.dedup.....10d8b41f37685ff77e3e6c1c24ad46d6