Carotenoid-Mediated Long-Range Energy Transfer in the Light Harvesting-Reaction Center Complex from Photosynthetic Bacterium Roseiflexus castenholzii.
J Phys Chem B
; 127(48): 10360-10369, 2023 Dec 07.
Article
in En
| MEDLINE
| ID: mdl-37983555
ABSTRACT
The light harvesting-reaction center complex (LH-RC) of Roseiflexus castenholzii binds bacteriochlorophylls a (BChls a), B800 and B880, absorbing around 800 and 880 nm, respectively. We comparatively investigated the interband excitation energy transfer (EET) dynamics of the wild-type LH-RC (wt-LH-RC) of Rfl. castenholzii and its carotenoid (Car)-less mutant (m-LH-RC) and found that Car can boost the B800 â B880 EET rate from (2.43 ps)-1 to (1.75 ps)-1, accounting for 38% acceleration of the EET process. Interestingly, photoexcitation of wt-LH-RC at 800 nm induced pronounced excitation dynamics of Car despite the insufficient photon energy for direct Car excitation, a phenomenon which is attributed to the BChl-Car exciplex 1[B800(↑↑)···Car(↓↓)]*. Such an exciplex is suggested to play an essential role in promoting the B800 â B880 EET process, as corroborated by the recently reported cryo-EM structures of wt-LH-RC and m-LH-RC. The mechanism of Car-mediated EET will be helpful to deepen the understanding of the role of Car in bacterial photosynthesis.
Full text:
1
Database:
MEDLINE
Main subject:
Photosynthesis
/
Chloroflexi
Language:
En
Year:
2023
Type:
Article