Inward H ⁺ pump xenorhodopsin: Mechanism and alternative optogenetic approach

Abstract

Neurons expressing a novel rhodopsin can be activated by light; a complete story of protein structure and function follows.

High Resolution Structural Insights into Heliorhodopsin Family

“…The widely spread presence and importance of pR-based phototrophy in the marine environment 17 was identified. Recently, rhodopsins that function as inward proton pumps were discovered 18,19 .…”

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

“…Here, we present a high-resolution structure of another viral rhodopsin from group 1 OLPVR1 at 1.4 Å resolution. The protein was crystallized with an in meso approach similar to that used in our previous studies (Gushchin et al, 2015;Shevchenko et al, 2017). We obtained three different types of crystals.…”

“…The plasmid was verified by sequencing. The protein was expressed as described previously (Shevchenko et al, 2017) subjected to size-exclusion chromatography on a 20 ml Superdex 200i 10/300 GL column (GE Healthcare Life Sciences) in a buffer containing 10 mM NaH 2 PO 4 /Na 2 HPO 4 , pH 8.0, 0.1 M NaCl and 0.05% DDM. Protein-containing fractions with an A 280 /A 500 absorbance ratio (peak ratio, p.r.)…”

“…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).…”

Light‐Controlled Mammalian Cells and Their Therapeutic Applications in Synthetic Biology

“…[6] Activated opsins of the type I family can function in various settings, such as light-driven pumps, light-gated channels, photosensors, and light-activated enzymes. So far, a number of microbial proton pumps (e.g., proteorhodopsin, [55] delta-rhodopsin, [56] xenorhodopsin [57] ) have been used in synthetic biology to pump protons in-/outward across the plasma membrane of cells in response to light. [5,6,11] Nevertheless, we would like to highlight the first identified microbial type I rhodopsin, bacteriorhodopsin (BR), which is a light-driven outward H + pump [53,54] (Figure 1c).…”