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## Acknowledgments

AO acknowledges financial support from National Science Centre, Poland, (grant 2015/18/A/NZ1/00046) and from Foundation for Polish Science (programme TEAM, POIR.04.04.00-00-5B54/17-00)

WAC acknowledges support for the research studies described in this Review, supported at different times by the U. S. National Institutes of Health/General Medical Sciences (GMS-038323) and the U. S. Dept. of Energy (DOE DE-SC0018238).

GF acknowledges support by the French national funding agency ANR ('Momix' Projet-ANR-17-CE05-0029); the excellence cluster LabEX GRAL (ANR-10-LABX-49-01 financed within the University Grenoble Alpes graduate school -Ecoles Universitaires de Recherche- CBH-EUR-GS ANR-17-EURE-0003) and the European Research Council (ERC AdG 'Chloro-mito', grant no. 833184)

## Short biographical notes

Marcin Sarewicz was born in Poland in 1979. In the years 2003 - 2007 he was a Ph.D. student at the Faculty of Biochemistry, Biophysics and Biotechnology of the Jagiellonian University in Krakow and his dissertation was awarded by "Prime Minister Award for the PhD thesis". After postdoctoral studies, he was employed as a lecturer at the same department, where he began working on the study of the molecular mechanisms of cytochrome *bc*₁ catalysis. In 2013 he obtained "Scientific Scholarchop for an outstanding young scientist" awarded by the Ministry of Science and Higher Education. In 2019 he obtained the degree of habilitated doctor, and currently he is an assistant professor at the Department of Molecular Biophysics. His research program focuses on the use of electron paramagnetic resonance in conjunction with rapid freezing techniques to study the molecular mechanisms of electron transfer processes in enzymes involved in cellular bioenergetics.

Sebastian Pintscher received his Ph.D. from the Jagiellonian University in 2016 for his work on the semiquinone intermediates of the cytochrome bc1. Currently he is a postdoctoral fellow at the
Jagiellonian University, pursuing research on the cyclic electron transfer in plant chloroplasts. His research interests include the redox chemistry of quinone oxidoreductases, properties of free-radical intermediates and evolution of bioenergetic systems.

Rafał Pietras (Kielce, Poland, 1985) graduated from Jagiellonian University in Kraków (Poland) where he also received his Ph.D. in biophysics in 2015. His research activities are focused around interactions between components of bioenergetic systems. In his scientific endeavour he applies EPR spectroscopy to investigate spin-labelled proteins and metaloenzymes. Currently he is involved in a project on the regulation of cyclic electron transfer in photosynthesis as a post-doc fellow at Jagiellonian University.

Arkadiusz Borek received a Ph.D. degree in biophysics from Jagiellonian University (Poland) in 2015. His PhD research was focused on the understanding of the mechanism of superoxide production by cytochrome bc1. He is a member of Molecular Bioenergetics Group of the Jagiellonian University led by prof. A. Osyczka. His postdoctoral studies concern the search for a mechanism of regulation of the operation of complex III. He is a grantee of the National Science Center, Poland. The topic of his project is understanding of the molecular effects of human mitochondrial cytochrome b mutations.

Łukasz Bujnowicz is currently a postdoc in Department of Molecular Biophysics at the Faculty of Biochemistry, Biophysics and Biotechnology of Jagiellonian University in Kraków. He received MSc (2013) and PhD in biophysics at the same faculty. The PhD thesis written by Łukasz was awarded as the best polish thesis in biochemistry in 2018 by The Polish Biochemical Society. He is interested in molecular mechanisms of electron transfer, development of methods of kinetic measurements with usage of Electron Paramagnetic Resonance combined with optical spectroscopy and occasionally image analysis but his passion is fly fishing.

Guy Hanke received his PhD from the University of Manchester in 1999 after working in the research groups of Professor Mike Emes and Caroline Bowsher. He then worked until 2008 first as a Japan Society of the Promotion of Science Research Fellow and Royal Society Research Fellow, then an Assistant Professor in the group of Professor Toshiharu Hase at Osaka University, before moving to
become an assistant in the group of Professor Renate Scheibe at the University of Osnabrueck. In 2015 he was appointed as a Senior Lecturer in Plant Cell and Molecular Biology at Queen Mary University of London. His research interest throughout his career has been how the distribution of energy - in particular electrons - is controlled within photosynthetic cells. This is explored using plant and cyanobacterial genetics, 'omics approaches, physiology and protein biochemistry to examine the function of proteins at the interface between energy generation in thylakoid membranes, and energy consumption by soluble enzymes.

William A. Cramer received a B. S. and M. S. in Physics from the Massachusetts Institute of Technology and the University of Chicago, respectively, the M. I. T. thesis on "anisotropy in the arrival direction of high energy cosmic rays." Initial studies were published on (a) "µ meson capture rates" and (b) "optical birefringence of muscle proteins." The Chicago Doctorate in Biophysics focused on photodynamically-induced mutagenesis of T4 bacteriophage. As an NSF postdoctoral Fellow with W. L. Butler at the University of California/San Diego, biophysical studies on the photosynthetic electron transport chain provided some of the first quantitative information on in situ properties of the cytochrome transport proteins. The latter studies became part of a research program subsequently pursued at Purdue University, where Cramer became Distinguished Professor of Biological Sciences, on structure-function of membrane proteins including membrane-active bactericidal toxins ("colicins"). These studies were recognized by Fellowships from the EMBO, and the Alexander von Humboldt and Guggenheim Foundations, by recognition as a 'Fellow' by (i) the American Association for the Advancement of Science (AAAS) and (ii) by the Biophysical Society for which Cramer participated in the establishment of the Bioenergetics Sub-Group of the Society and served as Chair, and (iii) by selection as Chair of two international Gordon Conferences on (1) "Biochemical Aspects of Photosynthesis," and (2) "Bioenergetics."

Giovanni Finazzi got his PhD in Cellular and Molecular Biology (specializing in biophysics) at the University of Milano (Italy), under the supervision of Giorgio Forti. After a post doc at the Institut de Biologie Physico Chimique (IBPC) in Paris on the biophysics of photosynthesis under the supervision of Pierre Joliot, he joined the Italian Research Council as a junior research scientist. He pursued his career in the French CNRS, first in Paris (IBPC) and then in the Laboratory of Plant and Cell Physiology of the CEA of Grenoble as a Research Director. His main interest is understanding how
photosynthetic organisms manage their energy resources to thrive in different environments. He has
studies photosynthetic light harvesting, electron transport, ATP synthesis and stress acclimation
responses using a multidisciplinary approach, including biophysics, photophysiology, cell and
molecular biology and 3D imaging.

Artur Osyczka is a professor in the Department of Molecular Biophysics at the Jagiellonian
University (JU) in Kraków. His interest in redox-active proteins dates back to his graduate studies. In
1999, he completed his doctoral degree in the group of professor Katsumi Matsuura at Tokyo
Metropolitan University working on bacterial photosynthetic reaction center. His post-doctoral work
(1999-2006), carried out at the University of Pennsylvania in the group of professor P. Leslie Dutton,
focused on molecular mechanism of energy conservation in cytochrome *bc*₁. In 2006 he established
the Laboratory of Molecular Bioenergetics which now constitutes the major part of the Department
of Molecular Biophysics at JU. He was twice the recipient of Senior Research Fellowship from the
Wellcome Trust (in 2006-2012 and in 2011-2016). His research aims at understanding operation of
energy conserving systems from the physico-chemical point of view and also in relation to cellular
physiology. The topics include enzymatic catalysis and regulation of respiratory and photosynthetic
protein complexes, electron and proton transfers, reactive oxygen species, mitochondrial diseases,
dynamics of macromolecular interactions in redox systems.
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