EMD-27382

Single-particle
2.89 Å
EMD-27382 Deposition: 19/06/2022
Map released: 05/04/2023
Last modified: 05/04/2023
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-27382

Helical rods of far-red light-absorbing allophycocyanin in Synechococcus sp.

EMD-27382

Single-particle
2.89 Å
EMD-27382 Deposition: 19/06/2022
Map released: 05/04/2023
Last modified: 05/04/2023
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Synechococcus sp. 63AY4M1
Sample: Far-red light allophycocyanin
Fitted models: 8ddy (Avg. Q-score: 0.6)

Deposition Authors: Gisriel CJ , Shen GS , Soulier NT , Flesher DA , Brudvig GW , Bryant DA
Helical allophycocyanin nanotubes absorb far-red light in a thermophilic cyanobacterium.
Gisriel CJ , Elias E , Shen G , Soulier NT , Flesher DA , Gunner MR , Brudvig GW , Croce R , Bryant DA
(2023) Sci Adv , 9 , eadg0251 - eadg0251
PUBMED: 36961897
DOI: doi:10.1126/sciadv.adg0251
ISSN: 2375-2548
Abstract:
To compete in certain low-light environments, some cyanobacteria express a paralog of the light-harvesting phycobiliprotein, allophycocyanin (AP), that strongly absorbs far-red light (FRL). Using cryo-electron microscopy and time-resolved absorption spectroscopy, we reveal the structure-function relationship of this FRL-absorbing AP complex (FRL-AP) that is expressed during acclimation to low light and that likely associates with chlorophyll a-containing photosystem I. FRL-AP assembles as helical nanotubes rather than typical toroids due to alterations of the domain geometry within each subunit. Spectroscopic characterization suggests that FRL-AP nanotubes are somewhat inefficient antenna; however, the enhanced ability to harvest FRL when visible light is severely attenuated represents a beneficial trade-off. The results expand the known diversity of light-harvesting proteins in nature and exemplify how biological plasticity is achieved by balancing resource accessibility with efficiency.