Starts 5 Oct 2022 11:00
Ends 5 Oct 2022 12:00
Central European Time
Virtual Seminar
via Zoom

Tjaart Krüger
(University of Pretoria, South Africa)
 

 
Abstract:
 
Photosynthetic light-harvesting complexes have to balance two vital functions: efficient light harvesting and efficient energy dissipation. The former occurs under low levels of solar radiation, during which the absorbed photoenergy is converted into chemical energy with near-unity quantum efficiency. The latter, finely tuned photoprotective function serves to safely remove excess absorbed energy to limit photodamage. The nature of both functions is a subject of intense research. The light-harvesting proteins commonly coordinate numerous chromophores in a dense arrangement, resulting in complex, coupled energy-transfer mechanisms. Consequently, transitions between the light-harvesting and photoprotective functions often involve only subtle protein conformational changes, i.e., the population equilibrium between different conformational states of light-harvesting proteins is often very sensitive to the protein’s local environment. Single-molecule spectroscopy uniquely allows one to monitor protein functional switches in real time, to explore the protein conformational landscapes, and to unravel the underlying photophysical processes. In this webinar I will show how the intrinsic disorder of photosynthetic proteins is regulated by their local environments, allowing them to switch between different light-harvesting and photoprotective states. The unstable equilibrium between different functional states can be finely tuned by the incident photon flux1, pH2, chromophore arrangement3, and interaction with accessory proteins4. Examples of environmentally controlled conformational switching, as assessed by single-molecule spectroscopy, will be given for light-harvesting complexes of plants, cyanobacteria, and diatoms.
 
References
  1. Gwizdala et al. J Am Chem Soc 138 (36): 11616-11622 (2016).
  2. Krüger et al. Biophys J 102: 2669–2676 (2012).
  3. Krüger et al. Proc Natl Acad Sci USA, 108:13516-13521 (2011); Krüger et al. Proc Natl Acad Sci USA 114: E11063-E11071 (2017).
  4. Gwizdala et al. J Phys Chem Lett 9:2426-2432 (2018).