Photoadaptation of robust C . merolae photosystem I 1 Molecular mechanisms of photoadaptation of photosystem 1 I supercomplex of in an evolutionary cyanobacterial / algal intermediate 2 3

PH, MA, LN, JK, JMK, EEl-M, and RK generated and processed the data and prepared the figures. 29 JDJO contributed to purification and biochemical characterisation PSI and studies on its interaction 30 with PBSs. JK, JMK, PH, RK, designed the experiments, analysed and interpreted the data. JMK, RK 31 and PH co-wrote the manuscript. JMK conceived and coordinated the study. 32 JMK, PH and MA acknowledge the support from the Polish National Science Centre (OPUS grant no. 33 UMO-2014/15/B/NZ1/00975 to JMK). Part of this work was also supported by the Polish Ministry of 34 Science and Higher Education and the European Science Foundation within the 35 Eurocores/EuroSolarFuels/Solarfueltandem programme (grant no. 844/N-ESF 36 EuroSolarFuels/10/2011/0 to JMK). The work of LK and RK was supported by grant LO1204 37 (Sustainable development of research in the Centre of the Region Haná) from the National Program of 38 Sustainability I from the Ministry of Education, Youth and Sports, Czech Republic. CIISB research 39 infrastructure project LM2015043 funded by MEYS CR is gratefully acknowledged for the financial 40 support of the measurements at the CF Cryo-electron Microscopy and Tomography. EEl-M 41 acknowledges the support from the Ministry of Higher Education Egypt. 42 43 Plant Physiology Preview. Published on November 29, 2017, as DOI:10.1104/pp.17.01022