Role of pheophytin a in the primary charge separation of photosystem I from Acaryochloris marina: Femtosecond optical studies of excitation energy and electron transfer reactions

Petrova, Anastasia; Casazza, Anna Paola; Шелаев, И. В.; Гостев, Ф. Е.; Aybush, Arseniy V.; Надточенко, В. А.; Semenov, Alexey Yu.; Santabarbara, Stefano; Cherepanov, Dmitry A.

doi:10.1016/j.bbabio.2023.148984

Cited by 6 publications

(1 citation statement)

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“…Recent structural analyses have also contributed to theoretical studies on the physical processes occurring within type-I RCs. ,,,,− Adolphs et al calculated the excitonic coupling strength between every pair of Chl a molecules on PSI using the Poisson TrESP (P-TrESP) method and obtained the spatial distribution of the site energy shift (SES) values using the charge density coupling (CDC) method. SES values indicate the differences in the electrostatic interactions between the excited and ground states of the Chl a molecules and the surrounding polypeptides.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Mutation of Exciton States on the Smallest Type-I Photosynthetic Reaction Center Complex of a Green Sulfur Bacterium Chlorobaclum tepidum

Kimura,

Kitoh-Nishioka,

Kondo

et al. 2024

J. Phys. Chem. B

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The exciton states on the smallest type-I photosynthetic reaction center complex of a green sulfur bacterium Chlorobaculum tepidum (GsbRC) consisting of 26 bacteriochlorophylls a (BChl a) and four chlorophylls a (Chl a) located on the homodimer of two PscA reaction center polypeptides were investigated. This analysis involved the study of exciton states through a combination of theoretical modeling and the genetic removal of BChl a pigments at eight sites. ( 1) A theoretical model of the pigment assembly exciton state on GsbRC was constructed using Poisson TrESP (P-TrESP) and charge density coupling (CDC) methods based on structural information. The model reproduced the experimentally obtained absorption spectrum, circular dichroism spectrum, and excitation transfer dynamics, as well as explained the effects of mutation. (2) Eight BChl a molecules at different locations on the GsbRC were selectively removed by genetic exchange of the His residue, which ligates the central Mg atom of BChl a, with the Leu residue on either one or two PscAs in the RC. His locations are conserved among all type-I RC plant polypeptide, cyanobacteria, and bacteria amino acid sequences. (3) Purified mutant-GsbRCs demonstrated distinct absorption and fluorescence spectra at 77 K, which were different from each other, suggesting successful pigment removal. (4) The same mutations were applied to the constructed theoretical model to analyze the outcomes of these mutations. (5) The combination of theoretical predictions and experimental mutations based on structural information is a new tool for studying the function and evolution of photosynthetic reaction centers.

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