Isolation and Characterization of Three Membrane-Bound Chlorophyll-Protein Complexes from Four Dinoflagellate Species

• Published in: Philosophical transactions of the Royal Society of London. Series B. Biological sciences Vol. 340; no. 1294; pp. 381 - 392
• Main Authors: IGLESIAS-PRIETO, R, GOVIND, N. S, TRENCH, R. K
• Format: Journal Article
• Language: English
• Published: London The Royal Society 29.06.1993; Royal Society of London
• Subjects: Absorption spectra; Algae; Apoproteins; Biological and medical sciences; Cell biochemistry; Cell physiology; Cell structures and functions; Chlorophylls; Chloroplast, photosynthetic membrane and photosynthesis; Emission spectra; Fluorescence; Fundamental and applied biological sciences. Psychology; Line spectra; Molecular and cellular biology; Plant physiology and development; Plants; Thylakoids; Wavelengths; Characterization; Spectral data; Algae; Pigment protein complex; Pyrrophycophyta; Isolation; Thylakoid; Thallophyta
• ISSN: 0962-8436; 1471-2970
• DOI: 10.1098/rstb.1993.0080

Employing discontinuous sucrose density gradient centrifugation of n-dodecyl $\beta$-d-maltoside-solubilized thylakoid membranes, three chlorophyll (Chl)-protein complexes containing Chl a, Chl c$_2$ and peridinin in different proportions, were isolated from the dinoflagellates Symbiodinium microadriaticum, S. kawagutii, S. pilosum and Heterocapsa pygmaea. In S. microadriaticum, the first complex, containing 13% of the total cellular Chl a, and minor quantities of Chl c$_2$ and peridinin, is associated with polypeptides with apparent molecular mass (M$_r$) of 8-9 kDa, and demonstrated inefficient energy transfer from the accessory pigments to Chl a. The second complex contains Chl a, Chl c$_2$ and peridinin in a molar ratio of 1:1:2, associated with two apoproteins of M$_r$ 19-20 kDa, and comprises 45%, 75% and 70%, respectively, of the cellular Chl a, Chl c$_2$ and peridinin. The efficient energy transfer from Chl c$_2$ and peridinin to Chl a in this complex is supportive of a light-harvesting function. This Chl a-c$_2$-peridinin-protein complex represents the major light-harvesting complex in dinoflagellates. The third complex obtained contains 12% of the cellular Chl a, and appears to be the core of photosystem I, associated with a light-harvesting complex. This complex is spectroscopically similar to analogous preparations from different taxonomic groups, but demonstrates a unique apoprotein composition. Antibodies against the water-soluble peridinin-Chl a-protein (sPCP) light-harvesting complexes failed to cross-react with any of the thylakoid-associated complexes, as did antibodies against Chl a-c-fucoxanthin apoprotein (from diatoms). Antibodies against the P$_{700}$ apoprotein of plants did not cross-react with the photosystem I complex. Similar results were observed in the other dinoflagellates.