Mechanism of Photosynthesis

How do FaRLiP cyanobacteria absorb far-red light for photosynthesis? Understanding how chlorophyll f, which assists in absorbing far-red light, binds to the photosystem among these cyanobacteria contributes to unraveling the mysteries of using far-red light. Additionally, our research focuses on the phycobilisome, a unique protein complex that aids in light absorption in cyanobacteria. Is there a variation in the function of phycobilisomes with different configurations in cyanobacteria of distinct species?

Relative Publications:

Gisriel CJ, Flesher DA, Shen G, Wang J, Ho M-Y, Brudvig GW, Bryant DA. (2021) Structure of a photosystem I-ferredoxin complex from a marine cyanobacterium provides insights into far-red light photoacclimation. J. Biol. Chem. 298, 101408. https://doi.org/10.1016/j.jbc.2021.101408
Gisriel CJ, Shen G, Kurashov V, Ho M-Y, Zhang S, Williams D, Golbeck JH, Fromme P, Bryant DA. (2020) Structure of photosystem I acclimated to far-red light. Sci. Adv. 6, eaay6415. https://doi.org/10.1126/sciadv.aay6415

Chlorophyll f binding sites in PSI

Chlorophyll f is one of the crucial factors allowing FaRLiP cyanobacteria to absorb far-red light. However, the specific locations of these pigments in photosystem I are not yet clear. By eliminating potential binding sites between chlorophyll f and photosystem I, and employing techniques such as spectroscopy, HPLC, and protein extraction, we will gain a better understanding of how chlorophyll f binds to photosystem I. This knowledge will be significantly helpful for expressing chlorophyll f in other species in the future.

Relative Publications:

Gisriel CJ, Cardona T, Bryant DA, & Brudvig GW. (2022) Molecular Evolution of Far-Red Light-Acclimated Photosystem II. Microorganisms. 10(7), 1270. https://doi.org/10.3390/microorganisms10071270
Gisriel CJ, Shen G, Ho M-Y, Kurashov V, Flesher DA, Wang J, Armstrong WH, Golbeck JH, Gunner MR, Vinyard DJ, Debus RJ, Brudvig GW, Bryant DA. (2021) Structure of a monomeric photosystem II core complex from a cyanobacterium acclimated to far-red light reveals the functions of chlorophylls d and f. J. Biol. Chem. 298, 101424. https://doi.org/10.1016/j.jbc.2021.101424

Site-directed mutagenesis in PSII

FaRLiP cyanobacteria are capable of absorbing far-red light for photosynthesis by remodeling the structures of photosystems I and II. We are curious about the crucial sites in photosystem II for absorbing far-red light or other physiological reactions. Through CRISPR/Cpf1 gene editing techniques, protein extraction, and pigment composition analysis, we can gain a deeper understanding of the critical sites in the photosystem of FaRLiP cyanobacteria.

Relative Publications:

Jiang H-W, Wu H-Y, Wang C-H, Yang C-H, Ko J-T, Ho H-C, Tsai M-D, Bryant DA, Li F-W, Ho M-C#, Ho M-Y# (2023) A structure of the relict phycobilisome from a thylakoid-free cyanobacterium. Nat. Commun. 14, 8009. https://doi.org/10.1038/s41467-023-43646-9. (#co-corresponding author)
Rahmatpour N, Hauser DA, Nelson JM, Chen PY, Villarreal JC, Ho M-Y#, Li F-W# (2021) A novel thylakoid-less isolate fills a billion-year gap in the evolution of Cyanobacteria. Curr. Biol. 31, 2857-2867.e4. https://doi.org/10.1016/j.cub.2021.04.042 (#co-corresponding author)
Jiang, H-W, Ho M-Y. (2021) Isolation and characterization of intact phycobilisome in cyanobacteria. J. Vis. Exp. (177):e63272. https://doi.org/10.3791/63272

Structure of Phycobilisome

Phycobilisomes are commonly found in most cyanobacteria, aiding in light absorption. Different cyanobacterial species exhibit diverse structures of phycobilisomes. We are dedicated to studying the unique phycobilisome structure of the recently discovered cyanobacterium A. panamensis. Through protein purification, cryo-electron microscopy, and other protein experimental techniques, we can explore a structure distinct from the typical fan-shaped or bundle-shaped phycobilisomes found in other cyanobacteria. This research contributes to a deeper understanding of the evolutionary history between cyanobacteria and phycobilisomes.

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