Dataset Information

Structure of a volume-regulated heteromeric LRRC8A/C channel

ABSTRACT: Volume-regulated anion channels participate in the cellular response to osmotic swelling. These membrane proteins are heteromers of LRRC8 family members whose composition determines permeation properties. Although structures of the obligatory LRRC8A subunit have previously defined the architecture of VRACs, the organization of heteromeric channels has remained elusive. Here we have closed this gap by the structural characterization of channels consisting of LRRC8A and C. Like homomeric LRRC8A, these proteins assemble as hexamers. Despite the twelve possible arrangements, we find a single predominant species with an A/C ratio of two. In this assembly, the four LRRCA subunits cluster in their preferred conformation observed in homomers as pairs of closely interacting proteins that stabilize a closed state of the channel. In contrast, the two interacting LRRC8C-subunits show a larger flexibility, underlining their role in the destabilization of the tightly packed A subunits, thereby enhancing the activation properties of the protein.

INSTRUMENT(S): Orbitrap Exploris 480

ORGANISM(S): Homo Sapiens (human) Mus Musculus (mouse)

TISSUE(S): Cell Culture

SUBMITTER: Antje Dittmann

LAB HEAD: Raimund Dutzler

PROVIDER: PXD035350 | Pride | 2023-01-03

REPOSITORIES: Pride

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Publications

Structure of a volume-regulated heteromeric LRRC8A/C channel.

Rutz Sonja S Deneka Dawid D Dittmann Antje A Sawicka Marta M Dutzler Raimund R

Nature structural & molecular biology 20221215 1

Volume-regulated anion channels (VRACs) participate in the cellular response to osmotic swelling. These membrane proteins consist of heteromeric assemblies of LRRC8 subunits, whose compositions determine permeation properties. Although structures of the obligatory LRRC8A, also referred to as SWELL1, have previously defined the architecture of VRACs, the organization of heteromeric channels has remained elusive. Here we have addressed this question by the structural characterization of murine LRR ...[more]

PMID: 36522427

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Project description:Background: The global demand for affordable carbon has never been stronger, and there is an imperative in many industrial processes to use waste streams to make products. Gas-fermenting acetogens offer a potential solution and several commercial gas fermentation plants are currently under construction. As energy limits acetogen metabolism, supply of H2 should diminish substrate loss to CO2 and facilitate production of reduced and energy-intensive products. However, the effects of H2 supply on CO-grown acetogens have yet to be experimentally quantified under controlled growth conditions. Results: Here, we quantify the effects of H2 supplementation by comparing growth on CO, syngas, and a high-H2 CO gas mix using chemostat cultures of Clostridium autoethanogenum. Cultures were characterised at the molecular level using metabolomics, proteomics, gas analysis, and a genome-scale metabolic model (GEM). CO-limited chemostats operated at two steady-state biomass concentrations facilitated co-utilisation of CO and H2. We show that H2 supply strongly impacts carbon distribution with a four-fold reduction in substrate loss as CO2 (61% vs. 17%) and a proportional increase of flux to ethanol (15% vs. 61%). Notably, H2 supplementation lowers the molar acetate/ethanol ratio by five-fold. At the molecular level, quantitative proteome analysis showed no obvious changes leading to these metabolic rearrangements suggesting the involvement of post-translational regulation. Metabolic modelling showed that H2 availability provided reducing power via H2 oxidation and saved redox as cells reduced all the CO2 to formate directly using H2 in the Wood-Ljungdahl pathway. Modelling further indicated that the methylene-THF reductase reaction was ferredoxin-reducing under all conditions. In combination with proteomics, modelling also showed that ethanol was synthesised through the acetaldehyde:ferredoxin oxidoreductase (AOR) activity. Conclusions: Our quantitative molecular analysis revealed that H2 drives rearrangements at several layers of metabolism and provides novel links between carbon, energy, and redox metabolism advancing our understanding of energy conservation in acetogens. We conclude that H2 supply can substantially increase the efficiency of gas fermentation and thus the feed gas composition can be considered an important factor in developing gas fermentation-based bioprocesses.

Dataset Information

Structure of a volume-regulated heteromeric LRRC8A/C channel

Publications

Structure of a volume-regulated heteromeric LRRC8A/C channel.

Similar Datasets

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