Livnat-Levanon, N. | Search bioRxiv

bioRxiv2025

Prokaryotic mechanosensitive channels mediate copper influx

Copper is an essential micronutrient in all kingdoms of life, requiring a meticulous balance between acquisition and toxic overload. While copper import in eukaryotes has been investigated extensively, few prokaryotic copper importers have been identified, leading to the notion that cytoplasmic copper uptake is unnecessary in prokaryotes. Here we report that mechanosensitive channels are key players in prokaryotic copper import. Deletion of the gene encoding the E. coli small mechanosensitive channel, EcMscS, leads to significantly reduced copper influx. Conversely, overexpression of EcMscS leads to increased copper influx, elevated intracellular copper content, and renders cells hypersensitive to copper. Furthermore, specific channel blockers and competing permeating ions inhibit EcMscS copper conductance, lowering intracellular copper accumulation and alleviating copper hypersensitivity. These findings extend beyond E. coli, as other prokaryotic small mechanosensitive channels of bacterial and archaeal origin also facilitate copper influx. Taken together, these results uncover a previously unknown moonlighting function for mechanosensitive channels as a pathway for prokaryotic copper uptake.

microbiology↗

bioRxiv2023

Computational analysis of long-range allosteric communications in CFTR

Malfunction of the CFTR protein results in cystic fibrosis, one of the most common hereditary diseases. CFTR functions as an anion channel, the gating of which is controlled by long- range allosteric communications. Allostery also has direct bearings on CF treatment: the most effective CFTR drugs modulate its activity allosterically. Herein, we integrated Gaussian Network Model, Transfer Entropy, and Anisotropic Normal Mode-Langevin dynamics and investigated the allosteric communications network of CFTR. The results are in remarkable agreement with experimental observations and mutational analysis and provide extensive novel insight. We identified residues that serve as pivotal allosteric sources and transducers, many of which correspond to disease causing mutations. We find that in the ATP-free form, dynamic fluctuations of the residues that comprise the ATP binding sites facilitate the initial binding of the nucleotide. Subsequent binding of ATP then brings to the fore and focuses dynamic fluctuations that were present in a latent and diffuse form in the absence of ATP. We demonstrate that drugs that potentiate CFTRs conductance do so not by directly acting on the gating residues, but rather by mimicking the allosteric signal sent by the ATP binding sites. We have also uncovered a previously undiscovered allosteric "hotspot" located proximal to the docking site of the phosphorylated Regulatory (R) domain, thereby establishing a molecular foundation for its phosphorylation- dependent excitatory role. This study unveils the molecular underpinnings of allosteric connectivity within CFTR and highlights a novel allosteric "hotspot" that could serve as a promising target for the development of novel therapeutic interventions.

biophysics↗