Vibrational Study of the Inward Proton Pump Xenorhodopsin NsXeR: Switch Order Determines Vectoriality.
J Mol Biol
; 436(5): 168447, 2024 03 01.
Article
en En
| MEDLINE
| ID: mdl-38244766
ABSTRACT
Common proton pumps, e.g. HsBR and PR, transport protons out of the cell. Xenorhodopsins (XeR) were the first discovered microbial rhodopsins which come as natural inward proton pumps. In this work we combine steady-state (cryo-)FTIR and Raman spectroscopy with time-resolved IR and UV/Vis measurements to roadmap the inward proton transport of NsXeR and pinpoint the most important mechanistic features. Through the assignment of characteristic bands of the protein backbone, the retinal chromophore, the retinal Schiff base and D220, we could follow the switching processes for proton accessibility in accordance with the isomerization / switch / transfer model. The corresponding transient IR signatures suggest that the initial assignment of D220 as the proton acceptor needs to be questioned due to the temporal mismatch of the Schiff base and D220 protonation steps. The switching events in the K-L and MCP-MEC transitions are finely tuned by changes of the protein backbone and rearrangements of the Schiff base. This finely tuned mechanism is disrupted at cryogenic temperatures, being reflected in the replacement of the previously reported long-lived intermediate GS* by an actual redshifted (O-like) intermediate.
Palabras clave
Texto completo:
1
Base de datos:
MEDLINE
Asunto principal:
Rodopsina
/
Bombas de Protones
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
J Mol Biol
Año:
2024
Tipo del documento:
Article
País de afiliación:
Alemania