Structural insights into ion conduction by channelrhodopsin 2

Abstract

The light-gated ion channel channelrhodopsin 2 (ChR2) from is a major optogenetic tool. Photon absorption starts a well-characterized photocycle, but the structural basis for the regulation of channel opening remains unclear. We present high-resolution structures of ChR2 and the C128T mutant, which has a markedly increased open-state lifetime. The structure reveals two cavities on the intracellular side and two cavities on the extracellular side. They are connected by extended hydrogen-bonding networks involving water molecules and side-chain residues. Central is the retinal Schiff base that controls and synchronizes three gates that separate the cavities. Separate from this network is the DC gate that comprises a water-mediated bond between C128 and D156 and interacts directly with the retinal Schiff base. Comparison with the C128T structure reveals a direct connection of the DC gate to the central gate and suggests how the gating mechanism is affected by subtle tuning of the Schiff base's interactions.

High Resolution Structural Insights into Heliorhodopsin Family

“…The crystals were grown with an in meso approach 14,41 , similar to that used in our previous work 16,23 .…”

QM/MM Photodynamics of Retinal in the Channelrhodopsin Chimera C1C2 with OM3/MRCI

“…This structure was used in numerous theoretical studies and also provided a template for homology modelling of other ChRs (e. g. ChR2). The crystal structure of ChR2 has been obtained very recently by Volkov et al …”

Viral channelrhodopsins: calcium-dependent Na+/K+selective light-gated channels

“…OLPVR1 molecules are nearly identical in both structures (root mean square deviation (RMSD) less than 0.2 Å), so hereafter, we refer to the structure from type A crystals as it has the highest resolution. Despite the fact that only one OLPVR1 protomer is present in the asymmetric unit, the crystal packing of the protein shows that OLPVR1 could be organized into homodimers, similar to those of CrChR2 (Kato et al, 2012;Volkov et al, 2017). These dimers might reflect the oligomeric state of the viral channelrhodopsin in the cell membrane (Extended Data Figure 8).…”

“…Microbial and animal rhodopsins (type-1 and 2 rhodopsins, respectively) comprise a superfamily of heptahelical (7-TM) transmembrane proteins covalently linked to a retinal chromophore (Ernst et al, 2014;Gushchin and Gordeliy, 2018). Type-1 rhodopsins are the most abundant light-harvesting proteins that have diverse functions, such as ion pumping, ion channeling, sensory and enzymatic activities (Gordeliy et al, 2002;Govorunova et al, 2015;Gushchin et al, 2013Gushchin et al, , 2015Kato et al, 2015;Kim et al, 2018;Mukherjee et al, 2019;Shevchenko et al, 2017;Volkov et al, 2017). The discovery, in 2000, of the light-driven pump proteorhodopsin (PR) in marine microbes triggered extensive search of metagenomes for light-activated proteins (Béjà et al, 2000).…”