Thursday, March 01, 2018, 3:00PM - 4:00PM
John H. Golbeck
SEEC Auditorium (C120)
The first photosynthetic organisms evolved as far back as 3.5 billion or more years ago, but the electron donors were probably hydrogen, hydrogen sulfide, and organic molecules synthesized by extant single celled chemotrophs, lithotrophs and phototrophs. When these highly reduced molecules were exhausted, the only readily available reductant would have been water, which is exceedingly difficult to oxidize. However, the side product of water
oxidation, dioxygen, is a highly reactive molecule, and evolutionary adaptations would have needed to take place for molecules, proteins and living organisms to survive in its presence. One of these adaptations would have taken place in the structure and function of the Type I photosynthetic reaction center that generates NADPH. In this seminar, I will draw on our recent work on the structure of the homodimeric reaction center from Heliobacterium modesticaldum and from older work on the structure of the heterodimeric Photosystem I in cyanobacteria to speculate how Type I reaction centers evolved to adapt to the onset of this highly reactive molecule.
Free and open to the public.