7L1E

The Crystal Structure of Bromide-Bound GtACR1

Summary for 7L1E

• Entry DOI: 10.2210/pdb7l1e/pdb
• Descriptor: Anion channelrhodopsin-1, BROMIDE ION, (2R)-2,3-dihydroxypropyl (9Z)-octadec-9-enoate, ... (5 entities in total)
• Functional Keywords: bromide-bound, anion tunnel, anion channel, rhodopsin, transport protein
• Biological source: Guillardia theta (Cryptophyte, Cryptomonas phi)
• Total number of polymer chains: 2
• Total formula weight: 63629.85

Authors

Li, H.,Huang, C.Y.,Wang, M.,Spudich, J.L.,Zheng, L. (deposition date: 2020-12-14, release date: 2021-05-26, Last modification date: 2023-10-18)

Primary citation

Li, H.,Huang, C.Y.,Govorunova, E.G.,Sineshchekov, O.A.,Yi, A.,Rothschild, K.J.,Wang, M.,Zheng, L.,Spudich, J.L.
The crystal structure of bromide-bound Gt ACR1 reveals a pre-activated state in the transmembrane anion tunnel.
Elife, 10:-, 2021

PubMed Abstract: The crystal structure of the light-gated anion channel ACR1 reported in our previous Research Article (Li et al., 2019) revealed a continuous tunnel traversing the protein from extracellular to intracellular pores. We proposed the tunnel as the conductance channel closed by three constrictions: C1 in the extracellular half, mid-membrane C2 containing the photoactive site, and C3 on the cytoplasmic side. Reported here, the crystal structure of bromide-bound ACR1 reveals structural changes that relax the C1 and C3 constrictions, including a novel salt-bridge switch mechanism involving C1 and the photoactive site. These findings indicate that substrate binding induces a transition from an inactivated state to a pre-activated state in the dark that facilitates channel opening by reducing free energy in the tunnel constrictions. The results provide direct evidence that the tunnel is the closed form of the channel of ACR1 and shed light on the light-gated channel activation mechanism.

PubMed: 33998458
DOI: 10.7554/eLife.65903

Experimental method

X-RAY DIFFRACTION (3.2 Å)