Difference in the Charge-Separation Energetics between Distinct Conformers in the PixD Photoreceptor.
J Phys Chem B
; 127(48): 10351-10359, 2023 Dec 07.
Article
en En
| MEDLINE
| ID: mdl-38014591
ABSTRACT
Blue light using flavin (BLUF) domain proteins are photoreceptors in various organisms. The PixD BLUF domain can adopt two conformations, W91out and W91in, with Trp91 either proximal or distal to flavin (FMN). Using a quantum mechanical/molecular mechanical/polarizable continuum model approach, the energetics of charge-separated and biradical states in the two conformations were investigated. In the W91out conformation, the charge-separated state (FMNâ¢-) is more stable than the photoexcited state (FMN*), whereas it is less stable due to an electrostatic repulsive interaction with the Ser28 side chain in the W91in conformation. This leads to a lower activation energy for the charge separation in the W91out conformation, resulting in a faster charge separation compared to that in the W91in conformation. In the W91out conformation, the radical state (FMNHâ¢) is more stable than FMNâ¢- and forms from FMNâ¢-, leading to reorientation of the Gln50 side chain adjacent to FMN and formation of a hydrogen bond between Gln50 and FMN. Subsequently, a signaling state forms through charge recombination. In contrast, in the W91in conformation, FMNâ¢- cannot proceed further, returning to the dark-adapted state, as FMNH⢠is less stable. Thus, formation of the signaling state exclusively occurs in the W91out conformation.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Fotorreceptores Microbianos
Idioma:
En
Revista:
J Phys Chem B
Asunto de la revista:
QUIMICA
Año:
2023
Tipo del documento:
Article
País de afiliación:
Japón