Abstract 1192 Antimalarial drug interaction insight – characterization of hemoglobin interactions with sulfadoxine and pyrimethamine

Photosynthesis is one of the most important biological processes on earth, responsible for the conversion of solar energy into useful chemical energy and the release of molecular oxygen as a byproduct for humans to breathe.Most organisms that perform oxygenic photosynthesis use chlorophyll (Chl) a to absorb light from 400 nm to 700 nm, the visible light spectrum.However, certain species of cyanobacteria adapt to shaded environments by additionally synthesizing Chls d or f, both of which absorb far-red light (FRL) (700 nm to 800 nm) to enrich the organism's absorbance cross section.Gaining an understanding of the molecular bases of how cyanobacteria use FRL and of the structures of the enzymes that bind Chls d and f have agricultural significance.For instance, increasing the absorbance cross section of a crop can lead to increased yields.The research in our lab aims to provide an architectural basis for engineering cyanobacteria's FRL properties to crops to maximize photosynthesis rate and improve biomass production, particularly those that grow under shaded conditions such as in a canopy.Previous cryo-EM work has revealed the molecular structure of FRL-absorbing photosystem I from the thermophilic cyanobacterium Fischerella thermalis PCC 7521.However, it is difficult to distinguish between Chls a and f, whose structures are very similar, especially considering the low resolution of that structure.Due to the challenges in distinguishing these chlorophyll types in cryo-EM, we plan to perform X-ray crystallography that is better suited for distinguishing Chl types.The photosystem I from this organism was specifically chosen because it has been shown to be especially stable.Here, we further characterize the FRLabsorbing photosystem I complex from Fischerella thermalis PCC 7521 using SDS-PAGE, LC MS/MS, and negative stain transmission electron microscopy as preliminary data for crystallization attempts.