Microbial rhodopsins are light-activated retinal-binding membrane proteins, providing a variety of ion transport and sensory functions to procaryotic and eukaryotic cells. They display several cases of convergent evolution, where the same function is produced by unrelated or very distant protein groups. For example, both schizorhodopsins and xenorhodopsins are inward proton pumps, while halorhodopsins and NTQ-rhodopsins are inward chloride pumps.<br/>Here we present yet another interesting case of convergent evolution, this time among sensory rhodopsins. Haloarchaeal type sensory rhodopsins interacting with membrane-embedded Htr transducers are well described, and are close relatives of halobacterial proton pump bacteriorhodopsin. The new group of sensory rhodopsins we describe here is a relative of proteobacterial proton pumps, proteorhodopsins, but also appear to interact with Htr-like transducers, even though likely through a unique mechanism, as they do not conserve the residues found important for interaction of haloarchaeal SRII and HtrII.<br/>Moreover, the new sensory rhodopsins have unique structural motifs and many novel residues conserved in the group, including those around the retinal chromophore. We describe various spectroscopic properties of the wild-type and mutant sensory(proteo)rhodopsins, which report on the unusual structure of the protein and its retinal chromophore, and demonstrate their interaction with cognate transducers. We also model the structures and interactions of the receptor and the transducer.

Biospectroscopic characterization of novel membrane photosensors

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.