Supramolecular Organization and Functional Implications of K⁺ Channel Clusters in Membranes

Abstract

The segregation of cellular surfaces in heterogeneous patches is considered to be a common motif in bacteria and eukaryotes that is underpinned by the observation of clustering and cooperative gating of signaling membrane proteins such as receptors or channels. Such processes could represent an important cellular strategy to shape signaling activity. Hence, structural knowledge of the arrangement of channels or receptors in supramolecular assemblies represents a crucial step towards a better understanding of signaling across membranes. We herein report on the supramolecular organization of clusters of the K+ channel KcsA in bacterial membranes, which was analyzed by a combination of DNP‐enhanced solid‐state NMR experiments and MD simulations. We used solid‐state NMR spectroscopy to determine the channel–channel interface and to demonstrate the strong correlation between channel function and clustering, which suggests a yet unknown mechanism of communication between K+ channels.

High-resolution NMR studies of antibiotics in cellular membranes

“…However, the 1 H-detected cellular spectrum did not allow investigating all nisin residues, and did not provide side chain data, which can often be critical for drug binding. In order to obtain this complementary information, we sought to use DNP enhancement, which can boost the NMR signals of biomolecules by orders of magnitude 39 – 46 . Combined with a high-field 800 MHz magnet 47 , 48 , we envisioned that DNP would provide sufficient sensitivity and resolution to study the nisin pore in cell membranes.…”

The Mechanisms of Action of Cationic Antimicrobial Peptides Refined by Novel Concepts from Biophysical Investigations

“…One approach to obtain well-resolved solidstate NMR spectra is to subject the sample to fast rotation around the magic angle. This method results in NMR spectra where only the isotropic chemical shifts remain which resemble those observed in solution, and similar concepts for assignment and structural analysis are used (Das et al 2015;Eddy et al 2015;Gopinath and Veglia 2015;Jaipuria et al 2017;Visscher et al 2017;Naito et al 2018).…”

Dynamic Nuclear Polarization / solid-state NMR of membranes. Thermal effects and sample geometry

“…Membrane proteins are particularly time consuming to study because they are difficult to over-express, label and purify, they usually occur at highly dilute concentrations in their native lipid bilayer environment [12], and they tend to adopt a number of conformational states [13,14]. A widespread solid-state NMR approach to investigate membrane polypeptides is the measurement of distances and torsion angles under magic angle sample spinning (MAS) [15][16][17][18][19]. A complementary technique is the investigation of uniaxially oriented bilayer samples which is used to study the structure, membrane topology, dynamics, conformational heterogeneity or topological exchange [20][21][22][23].…”