Journal
PHOTOSYNTHESIS RESEARCH
Volume 151, Issue 1, Pages 11-30Publisher
SPRINGER
DOI: 10.1007/s11120-021-00871-x
Keywords
Reaction center; Heliobacteria; CRISPR-Cas; Excitonically coupled chlorophyll; uphill energy transfer; Supernumerary subunits
Categories
Funding
- Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences of the US Department of Energy [DE-SC0010575]
Ask authors/readers for more resources
The study reveals that PshX in Heliobacterium modesticaldum acts as a low-energy antenna subunit involved in energy transfer process. The research also demonstrates the importance of PshX in the stability and evolution of HbRC.
The anoxygenic phototrophic bacterium Heliobacterium modesticaldum contains a photochemical reaction center protein complex (called the HbRC) consisting of a homodimer of the PshA polypeptide and two copies of a newly discovered polypeptide called PshX, which is a single transmembrane helix that binds two bacteriochlorophyll g molecules. To assess the function of PshX, we produced a increment pshX strain of Hbt. modesticaldum by leveraging the endogenous Hbt. modesticaldum Type I-A CRISPR-Cas system to aid in mutant selection. We optimized this system by separating the homologous recombination and CRISPR-based selection steps into two plasmid transformations, allowing for markerless gene replacement. Fluorescence and low-temperature absorbance of the purified HbRC from the wild-type and increment pshX strains showed that the bacteriochlorophylls bound by PshX have the lowest site energies in the entire HbRC. This indicates that PshX acts as a low-energy antenna subunit, participating in entropy-assisted uphill energy transfer toward the P-800 special bacteriochlorophyll g pair. We further discuss the role that PshX may play in stability of the HbRC, its conservation in other heliobacterial species, and the evolutionary pressure to produce and maintain single-TMH subunits in similar locations in other reaction centers.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available