The Centre of New Technologies, University of Warsaw invites to a seminar by
Prof. dr hab. Artur Osyczka
Department of Molecular Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
Title: Spectroscopic insights into molecular operation of cytochrome complexes of photosynthetic and respiratory systems
Date: 7th of December 2023, Thursday
Time: 1:00-2:00 pm (CET)
Host: Prof. Joanna Kargul
The seminar will be held in the main CeNT lecture hall (00.142) on the ground floor.
Energy-converting systems of photosynthesis and respiration couple electron and proton transfers to generate protonmotive force that powers cellular metabolism. These systems are composed of the enzymatic complexes embedding metal centers that enable specific electron and proton transfer reactions. In our research we explore molecular mechanisms of operation of such metalloproteins using various spectroscopic methods, in particular optical and electron paramagnetic resonance spectroscopy. Our particular focus is on enzymes that use quinols as substrates. They are ubiquitous, as quinone is of the most universal chemical compound present in membranes. They functionally link the enzymatic complexes and engage in redox reactions
contributing to generation of protonmotive force. I will reflect on recent advances in understanding of molecular operation of three representatives of quinol oxidoreducatses that are being investigated in our laboratory: cytochrome bc 1 (mitochondrial complex III) that is part of respiratory chain (or photosynthetic chain in some bacteria), its photosynthetic counterpart – cytochrome b 6 f, and alternative complex III (ACIII) present in some bacterial chains. First two protein complexes belong to the family of cytochromes bc and are presumed to operate according to the same catalytic mechanism, although they feature intriguing structural differences of yet undefined function. ACIII is structurally unrelated to cytochromes bc and its mechanism is entirely unknown. I will discuss some aspects of inter-monomer electron transfer in dimeric cytochromes bc, mechanisms of oxidation of quinol and reduction of quinone -the two opposing redox reactions that are part of the catalytic cycle of these complexes, and mechanism of reactive oxygen species generation. I will also discuss the emerging new differences between cytochrome bc 1 and cytochrome b 6 f. I will show the progress in functional studies on ACIII that become possible due to the development of the first system for genetic manipulations of this complex.