Showing papers by "Christian Griesinger published in 2023"
TL;DR: In this article , the authors used solid-state NMR in conjunction with crystallography, solution NMR and distance measurements to investigate the transmembrane signaling mechanism of a paradigmatic citrate sensing membrane embedded HK, CitA.
Abstract: Membrane bound histidine kinases (HKs) are ubiquitous sensors of extracellular stimuli in bacteria. Here, we used solid-state NMR in conjunction with crystallography, solution NMR and distance measurements to investigate the transmembrane signaling mechanism of a paradigmatic citrate sensing membrane embedded HK, CitA. Citrate binding in the sensory extracytoplasmic PAS domain (PASp) causes the linker to transmembrane helix 2 (TM2) to adopt a helical conformation. This triggers a piston-like pulling of TM2 and a quaternary structure rearrangement in the cytosolic PAS domain (PASc). Crystal structures of PASc reveal both anti-parallel and parallel dimer conformations. An anti-parallel to parallel transition upon citrate binding agrees with interdimer distances measured in the lipid embedded protein using a site-specific 19F label in PASc. These data show how Angstrom scale structural changes in the sensor domain are transmitted across the membrane to be converted and amplified into a nm scale shift in the linker to the phosphorylation subdomain of the kinase. One-Sentence Summary Transmembrane signal transduction of a PAS-domain containing histidine kinase occurs via a piston-like pulling of a transmembrane helix, and amplification by cytoplasmic PAS domain dimer rearrangement.
1 citations
TL;DR: In this article , the authors demonstrate the efficacy of nonuniform sampling (NUS) in 2D correlation spectroscopy (COSY), which reduces the measurement time by half without compromising spectral quality and enhances the signal intensity for the given experiment time.
Abstract: An in‐depth structural characterization of marine dissolved organic matter (DOM) is crucial for a better understanding of its connection to marine and global biogeochemical cycles. High‐field nuclear magnetic resonance (NMR) spectroscopy in general and two‐dimensional (2D) correlation spectroscopy (COSY) in particular are powerful tools for the molecular level structural analysis of marine DOM. These 2D NMR experiments demand prolonged experimental times of days to weeks per sample due to the requirement of a large number of experiments to record the second dimension (t1) of the 2D NMR experiment. Herein, we demonstrate the efficacy of nonuniform sampling (NUS) in 2D COSY, which (i) reduces the measurement time by half without compromising spectral quality and (ii) enhances the signal intensity for the given experiment time. This approach can lead to substantial progress in the structural analysis of previously poorly characterized marine DOM. NUS COSY has been exemplified on two solid‐phase extracted DOM samples from the surface and deep ocean at 800 MHz and 1.2 GHz instruments. A dramatic improvement in sensitivity and spectral resolution is observed in NUS COSY spectra recorded at 1.2 GHz instrument when compared to 800 MHz instrument. NUS COSY NMR is versatile and anticipated to have significant potential for uncovering the hidden molecular diversity of DOM from various aquatic environments within a reasonable timeframe. The introduction of NUS into the environmental sciences was long overdue, and our study now opens the door for a wide field of new applications of NMR in the marine and aquatic sciences.
TL;DR: In this paper , the structure of lumnitzeralactone (1), a proton-deficient and highly challenging condensed aromatic ring system, was unambiguously elucidated by extensive spectroscopic analyses involving high-resolution mass spectrometry (HRMS), 1D 1H and 13C nuclear magnetic resonance spectroscopy (NMR), and 2D NMR.
Abstract: The previously undescribed natural product lumnitzeralactone (1), which represents a derivative of ellagic acid, was isolated from the anti-bacterial extract of the Indonesian mangrove species Lumnitzera racemosa Willd. The structure of lumnitzeralactone (1), a proton-deficient and highly challenging condensed aromatic ring system, was unambiguously elucidated by extensive spectroscopic analyses involving high-resolution mass spectrometry (HRMS), 1D 1H and 13C nuclear magnetic resonance spectroscopy (NMR), and 2D NMR (including 1,1-ADEQUATE and 1,n-ADEQUATE). Determination of the structure was supported by computer-assisted structure elucidation (CASE system applying ACD-SE), density functional theory (DFT) calculations, and a two-step chemical synthesis. Possible biosynthetic pathways involving mangrove-associated fungi have been suggested.
TL;DR: In this article , the authors introduce signalenhanced or hyperpolarized, nuclear magnetic resonance (NMR) to study hydrogenases under turnover conditions and reveal undiscovered hydrogen species of the catalytic cycle of [Fe]-hydrogenases, thus, extending the knowledge regarding this class of enzymes.
Abstract: Molecular hydrogen (H2) is considered an eco-friendly future energy-carrier and an alternative to fossil fuel1 and thus, major efforts are directed towards identifying efficient and economical hydrogen catalysts.2,3 Efficient hydrogen catalysis is used by many microorganisms, some of them producing H2 from organic materials and others consuming it.4-6 To metabolize H2, these microorganisms use enzymes called hydrogenases.7,8 For the future development of efficient catalysts a detailed analysis of the catalytic mechanisms of such hydrogenases is required and existing analytical techniques could not provide a full understanding.9 Consequently, new analytical technologies are of utmost importance to unravel natures’ blueprints for highly efficient hydrogen catalysts. Here, we introduce signal-enhanced or hyperpolarized, nuclear magnetic resonance (NMR) to study hydrogenases under turnover conditions. So far undiscovered hydrogen species of the catalytic cycle of [Fe]-hydrogenases, are revealed and thus, extend the knowledge regarding this class of enzymes. These findings pave new pathways for the exploration of novel hydrogen metabolisms in vivo. We furthermore envision that the results contribute to the rational design of future catalysts to solve energy challenges of our society.
TL;DR: In this article , the MINFLUX fluorescence nanoscopy was used to measure intra-molecular distances down to 1 nm and in planar projections to 1 Angström.
Abstract: Optical investigations of nanometer distances between proteins, their subunits, or other biomolecules have been the exclusive prerogative of Förster Resonance Energy Transfer (FRET) microscopy for decades. Here we show that MINFLUX fluorescence nanoscopy measures intra-molecular distances down to 1 nm – and in planar projections down to 1 Angström – directly, linearly, and with Angström precision. Our method is validated by quantifying well-characterized 1-to-10 nm distances in polypeptides and proteins. Moreover, we visualize the orientations of immunoglobulin subunits and reveal specific configurations of a histidine kinase domain dimer. Our results open the door for examining proximities and interactions of macromolecules under physiological conditions.
TL;DR: In this article , the authors grow amyloid-β (Aβ)40 fibrils in the presence of lipid vesicles and determined their structure by cryo-electron microscopy (cryo-EM) to high resolution.
Abstract: Alzheimer’s disease (AD) is a progressive and incurable neurodegenerative disease characterized by the extracellular deposition of amyloid plaques. Investigation into the composition of these plaques revealed a high amount of amyloid-β (Aβ) fibrils and a high concentration of lipids, suggesting that fibril-lipid interactions may also be relevant for the pathogenesis of AD. Therefore, we grew Aβ40 fibrils in the presence of lipid vesicles and determined their structure by cryo-electron microscopy (cryo-EM) to high resolution. The fold of the major polymorph is similar to the structure of brain-seeded fibrils reported previously. The majority of the lipids are bound to the fibrils as we show by cryo-EM and NMR spectroscopy. This apparent lipid extraction from vesicles observed here in vitro provides structural insights into potentially disease-relevant fibril-lipid interactions.
TL;DR: In this paper , the small central pyrazole moiety of anle138b is detected in close proximity to the protein backbone and differences in the contacts between fibrils and early intermediates are observed.
TL;DR: In this paper , the preclinical evaluation of MODAG-005 as a promising α-synuclein PET tracer is presented. But, it is not shown that the tracer has high affinity binding to α-SYN.
Abstract: Ziel/Aim PET imaging of alpha-synuclein (αSYN) aggregates would be a game changer for facilitating the diagnosis of synucleinopathies and the development of novel therapies. We previously demonstrated that the structural modification of anle138b, an investigational therapeutic for synucleinopathies [1], led to radiotracer candidates with high-affinity binding to αSYN [2] [3]. Here, we report the preclinical evaluation of MODAG-005 as a promising αSYN PET tracer.