Papers by Gebhard F X Schertler
Oxford University Press eBooks, May 8, 2003
A fundamental aim in vision research is to elucidate the factors that subtly modify the absorptio... more A fundamental aim in vision research is to elucidate the factors that subtly modify the absorption maxima of the visual pigments — the G protein-coupled receptors (GPCRs) responsible for transducing visual stimuli. Humans have four visual pigments, found in the two classes of retinal cells responsible for light detection: rod cells for dim light detection and cones for colour vision. Human rod cells contain rhodopsin, which is important for vision in dim light and is currently the most intensively studied visual pigment. This chapter reviews the structural work that has been carried out on rhodopsin, with a view towards spectral tuning.
bioRxiv (Cold Spring Harbor Laboratory), Jun 23, 2020
Current Opinion in Structural Biology, Aug 1, 2015
Investigative Ophthalmology & Visual Science, May 14, 2008
Proceedings of the National Academy of Sciences of the United States of America, Apr 3, 2023
Calmodulin (CaM) regulates many ion channels to control calcium entry into cells, and mutations t... more Calmodulin (CaM) regulates many ion channels to control calcium entry into cells, and mutations that alter this interaction are linked to fatal diseases. The structural basis of CaM regulation remains largely unexplored. In retinal photoreceptors, CaM binds to the CNGB subunit of cyclic nucleotide-gated (CNG) channels and, thereby, adjusts the channel’s Cyclic guanosine monophosphate (cGMP) sensitivity in response to changes in ambient light conditions. Here, we provide the structural characterization for CaM regulation of a CNG channel by using a combination of single-particle cryo-electron microscopy and structural proteomics. CaM connects the CNGA and CNGB subunits, resulting in structural changes both in the cytosolic and transmembrane regions of the channel. Cross-linking and limited proteolysis-coupled mass spectrometry mapped the conformational changes induced by CaM in vitro and in the native membrane. We propose that CaM is a constitutive subunit of the rod channel to ensure high sensitivity in dim light. Our mass spectrometry-based approach is generally relevant for studying the effect of CaM on ion channels in tissues of medical interest, where only minute quantities are available.
Structural Dynamics, May 1, 2023
Low-pass spectral analysis (LPSA) is a recently developed dynamics retrieval algorithm showing ex... more Low-pass spectral analysis (LPSA) is a recently developed dynamics retrieval algorithm showing excellent retrieval properties when applied to model data affected by extreme incompleteness and stochastic weighting. In this work, we apply LPSA to an experimental time-resolved serial femtosecond crystallography (TR-SFX) dataset from the membrane protein bacteriorhodopsin (bR) and analyze its parametric sensitivity. While most dynamical modes are contaminated by nonphysical high-frequency features, we identify two dominant modes, which are little affected by spurious frequencies. The dynamics retrieved using these modes shows an isomerization signal compatible with previous findings. We employ synthetic data with increasing timing uncertainty, increasing incompleteness level, pixel-dependent incompleteness, and photon counting errors to investigate the root cause of the high-frequency contamination of our TR-SFX modes. By testing a range of methods, we show that timing errors comparable to the dynamical periods to be retrieved produce a smearing of dynamical features, hampering dynamics retrieval, but with no introduction of spurious components in the solution, when convergence criteria are met. Using model data, we are able to attribute the high-frequency contamination of low-order dynamical modes to the high levels of noise present in the data. Finally, we propose a method to handle missing observations that produces a substantial dynamics retrieval improvement from synthetic data with a significant static component. Reprocessing of the bR TR-SFX data using the improved method yields dynamical movies with strong isomerization signals compatible with previous findings.
bioRxiv (Cold Spring Harbor Laboratory), Nov 27, 2020
Structural Dynamics, Jul 1, 2022
Nature Structural & Molecular Biology, Dec 30, 2021
In rod photoreceptors of the retina, the cyclic nucleotide-gated (CNG) channel is composed of thr... more In rod photoreceptors of the retina, the cyclic nucleotide-gated (CNG) channel is composed of three CNGA and one CNGB subunits, and it closes in response to light activation to generate an electrical signal that is conveyed to the brain. Here we report the cryo-EM structure of the closed state of the native rod CNG channel isolated from bovine retina. The structure reveals differences between CNGA1 and CNGB1 subunits. Three CNGA1 subunits are tethered at their C terminus by a coiled-coil region. The C-helix in the cyclic nucleotide-binding domain of CNGB1 features a different orientation from that in the three CNGA1 subunits. The arginine residue R994 of CNGB1 reaches into the ionic pathway and blocks the pore, thus introducing an additional gate, which is different from the central hydrophobic gate known from homomeric CNGA channels. These results address the long-standing question of how CNGB1 subunits contribute to the function of CNG channels in visual and olfactory neurons. The cryo-EM structure of the bovine rod CNG channel, isolated from retina, sheds light onto the structural basis for the subunit stoichiometry and reveals an additional gate within the ion conduction pathway contributed by the CNGB1 subunit.
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Papers by Gebhard F X Schertler