Structures of the archaerhodopsin-3 transporter reveal that disordering of internal water networks underpins receptor sensitization.

ABSTRACT: Many transmembrane receptors have a desensitized state, in which they are unable to respond to external stimuli. The family of microbial rhodopsin proteins includes one such group of receptors, whose inactive or dark-adapted (DA) state is established in the prolonged absence of light. Here, we present high-resolution crystal structures of the ground (light-adapted) and DA states of Archaerhodopsin-3 (AR3), solved to 1.1 Å and 1.3 Å resolution respectively. We observe significant differences between the two states in the dynamics of water molecules that are coupled via H-bonds to the retinal Schiff Base. Supporting QM/MM calculations reveal how the DA state permits a thermodynamic equilibrium between retinal isomers to be established, and how this same change is prevented in the ground stat

SUBMITTER: Bada Juarez JF 

PROVIDER: S-EPMC7840839 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature