Identification of a small-conductance mechanosensitive channel that plays a role in L-glutamate export in Bacillus methanolicus

ABSTRACT: Several small-conductance mechanosensitive channels (MscS) are well-researched l-glutamate exporters in bacterial workhorses employed in industrial biotechnology. Bacillus methanolicus, a methylotrophic bacterium, holds promise as a sustainable platform for l-glutamate bioprocesses utilizing methanol as a feedstock. Our research on B. methanolicus MGA3 identifies its MscS as the sole mechanosensitive channel in this organism and a key exporter of the amino acid l-glutamate, providing valuable insights into its potential for industrial applications. Transcriptomic analysis of B. methanolicus wild type cultured on an l-glutamate production medium revealed downregulation of fatty acid biosynthesis genes, suggesting that fatty acid metabolism is influenced by l-glutamate overproduction, with consequent changes in membrane fluidity likely driving mechanosensitive channel-mediated l-glutamate efflux. The MscS-like channel in B. methanolicus shares structural and functional similarities with MscS in Escherichia coli and Corynebacterium glutamicum. In silico structural predictions show that MGA3 MscS forms a homoheptameric structure with a transmembrane TM-barrel, resembling that of E. coli MscS. The opening mechanism of the channel, driven by membrane dynamics, involves coordinated rotation and flipping of its transmembrane helices, with variations in lipid composition potentially influencing the channel’s activity. Additionally, excess supplementation of biotin, a crucial coenzyme for fatty acid biosynthesis’ carboxylases, led to reduced l-glutamate biosynthesis in MGA3. Finally, metabolic engineering experiments inducing MscS gain- and loss-of-function further confirmed the channel’s critical role in B. methanolicus amino acid production, proportionally enhancing and reducing l-glutamate efflux, respectively. These findings open doors to novel strategies for engineering B. methanolicus and related methylotrophic organisms for efficient production and export of amino acids and other value-added products.

ORGANISM(S): Bacillus methanolicus

PROVIDER: GSE301205 | GEO | 2025/12/02

REPOSITORIES: GEO