Stages of OCP-FRP Interactions in the Regulation of Photoprotection in Cyanobacteria, Part 2: Small-Angle Neutron Scattering with Partial Deuteration.
J Phys Chem B
; 127(9): 1901-1913, 2023 03 09.
Article
em En
| MEDLINE
| ID: mdl-36815674
ABSTRACT
We used small-angle neutron scattering partially coupled with size-exclusion chromatography to unravel the solution structures of two variants of the Orange Carotenoid Protein (OCP) lacking the N-terminal extension (OCP-ΔNTE) and its complex formation with the Fluorescence Recovery Protein (FRP). The dark-adapted, orange form OCP-ΔNTEO is fully photoswitchable and preferentially binds the pigment echinenone. Its complex with FRP consists of a monomeric OCP component, which closely resembles the compact structure expected for the OCP ground state, OCPO. In contrast, the pink form OCP-ΔNTEP, preferentially binding the pigment canthaxanthin, is mostly nonswitchable. The pink OCP form appears to occur as a dimer and is characterized by a separation of the N- and C-terminal domains, with the canthaxanthin embedded only into the N-terminal domain. Therefore, OCP-ΔNTEP can be viewed as a prototypical model system for the active, spectrally red-shifted state of OCP, OCPR. The dimeric structure of OCP-ΔNTEP is retained in its complex with FRP. Small-angle neutron scattering using partially deuterated OCP-FRP complexes reveals that FRP undergoes significant structural changes upon complex formation with OCP. The observed structures are assigned to individual intermediates of the OCP photocycle in the presence of FRP.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Cianobactérias
Idioma:
En
Ano de publicação:
2023
Tipo de documento:
Article