Structure and function of photosystem I in Cyanidioschyzon merolae
- 147 Downloads
The evolution of photosynthesis from primitive photosynthetic bacteria to higher plants has been driven by the need to adapt to a wide range of environmental conditions. The red alga Cyanidioschyzon merolae is a primitive organism, which is capable of performing photosynthesis in extreme acidic and hot environments. The study of its photosynthetic machinery may provide new insight on the evolutionary path of photosynthesis and on light harvesting and its regulation in eukaryotes. With that aim, the structural and functional properties of the PSI complex were investigated by biochemical characterization, mass spectrometry, and X-ray crystallography. PSI was purified from cells grown at 25 and 42 °C, crystallized and its crystal structure was solved at 4 Å resolution. The structure of C. merolae reveals a core complex with a crescent-shaped structure, formed by antenna proteins. In addition, the structural model shows the position of PsaO and PsaM. PsaG and PsaH are present in plant complex and are missing from the C. merolae model as expected. This paper sheds new light onto the evolution of photosynthesis, which gives a strong indication for the chimerical properties of red algae PSI. The subunit composition of the PSI core from C. merolae and its associated light-harvesting antennae suggests that it is an evolutionary and functional intermediate between cyanobacteria and plants.
KeywordsPhotosynthesis Photosystem I Crystal structure Synechocystis Cyanobacteria Membrane complexes
The authors would like to thank the ESRF, SLS, and BESSYII synchrotrons for beam time and the staff scientists for excellent guidance and assistance. This work was supported by a grant (No. 293579 – HOPSEP) from the European Research Council, by The Israel Science Foundation (Grant No. 569/17), and by the I-CORE Program of the Planning and Budgeting Committee and The Israel Science Foundation (Grant No. 1775/12). M.H acknowledges funding by the German Science Foundation (DFG HI 739/13.1).
- Alboresi A, Le Quiniou C, Yadav SK, Scholz M, Meneghesso A, Gerotto C, Simionato D, Hippler M, Boekema EJ, Croce R, Morosinotto T (2017) Conservation of core complex subunits shaped the structure and function of photosystem I in the secondary endosymbiont alga Nannochloropsis gaditana. New Phytol 213, 714–726CrossRefPubMedGoogle Scholar
- DeLano WL (2002) Pymol: an open-source molecular graphics tool. Scientific, San CarlosGoogle Scholar
- Haniewicz P, Abram M, Nosek L, Kirkpatrick J, El-Mohsnawy E, Janna Olmos JD, Kouril R, Kargul JM. (2017) Molecular mechanisms of photoadaptation of photosystem I supercomplex of in an evolutionary cyanobacterial/algal intermediate. Plant Physiol 01022Google Scholar
- Malavath T, Caspy I, Netzer-El SY et al (2018) Structure and function of wild-type and subunit-depleted photosystem I in Synechocystis. Biochim Biophys Acta 0–1Google Scholar
- Mazor Y, Borovikova A, Caspy I, Nelson N (2017a) Structure of the plant photosystem i supercomplex at 2.6 Å resolution. Nat Plants 3:1–9Google Scholar
- Michel H, Ostermeier C Crystallization of membrane proteins. Biophys Methods 697–700 (1997)Google Scholar
- Sommer F, Drepper F, Haehnell W, Hippler M (2004) The hydrophobic recognition site formed by residues PsaA-Trp651 and PsaB-Trp627 of photosystem I in Chlamydomonas reinhardtii confers distinct selectivity for binding of plastocyanin and cytochrome c6. J Biol Chem 279:20009–20017CrossRefPubMedGoogle Scholar