Phycobilisomes attach to cellular membranes where the light-dependent reactions of photosynthesis take place. Changing the antenna complexes of the phycobilisomes can have dramatic and far-reaching consequences in cyanobacteria. Artificially modifying phycobilisomes by deleting certain genes in the cells caused structural defects in the cellular membranes and other cell physiology, allowing scientists to observe the resulting structural changes.
Starving the cyanobacteria for nitrogen naturally modifies the antenna complexes, causing the antenna to decrease in size and leading to significant cellular membrane modifications, because the cells break down the phycobilisomes and use them as an alternative nitrogen source to survive. By determining the extent of these changes, the team hopes to better understand the structure-function relationship between cellular organization and natural modification. These processes can be immediately reversed by restoring nitrogen to the cells. The researchers plan to compare these results to those recorded from their genetic studies to explore the differences between artificial and natural modifications and their effects on the intracellular makeup of cyanobacteria.
Instruments and Facilities Used: Photosynthetic Antenna Research Center (PARC), a DOE BES-funded Energy Frontier Research Center based at Washington University at St Louis. Small angle neutron scattering (SANS) was performed at the DOE-BER supported Bio-SANS instrument, beamline CG-3, at Oak Ridge National Laboratory’s High Flux Isotope Reactor.