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Phycoerythrin Association with Photosystem II in the Cryptophyte Alga Rhodomonas salina
I N Stadnichuk1, T M Novikova2, G S Miniuk2
1Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, 127726, Russia. stadnichuk@mail.ru.
Biochemistry. Biokhimiia
|June 27, 2020
Summary
Cryptophyte algae possess unique pigments. This study reveals their photosystem II ratio is 1:4, with light-harvesting phycoerythrin-545 exclusively associated with photosystem II.
Area of Science:
- Photosynthesis research
- Algal biology
- Biochemistry
Background:
- Cryptophyte algae have unique pigment compositions in their plastids, including phycobiliproteins and chlorophyll a/c.
- Despite advances in cryptophyte morphology, ecology, and systematics, their photosynthetic apparatus is not well understood.
- The ratio of photosystems I and II (PSI to PSII) and the roles of their antenna complexes are inconsistently reported.
Purpose of the Study:
- To investigate the photosynthetic apparatus of the cryptophyte alga Rhodomonas salina.
- To determine the ratio of photosystem I to photosystem II in R. salina.
- To elucidate the association of the phycobiliprotein antenna with photosystems.
Main Methods:
- Biochemical analysis of thylakoid membranes from Rhodomonas salina.
- Quantification of photosystem I and photosystem II ratios.
- Characterization of antenna pigment-protein complex associations.
Main Results:
- The photosystem I to photosystem II ratio in Rhodomonas salina thylakoid membranes was determined to be 1:4.
- This ratio contrasts significantly with cyanobacteria (3:1) and higher plants (1:1).
- The phycobiliprotein antenna, phycoerythrin-545, was found exclusively associated with photosystem II, not photosystem I.
Conclusions:
- Rhodomonas salina exhibits a distinct photosystem stoichiometry compared to other oxygenic phototrophs.
- The specific association of phycoerythrin-545 with photosystem II suggests a unique spatial organization within cryptophyte thylakoids.
- This organization may limit the interaction of the phycobiliprotein antenna with photosystem I.
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