Bilayer-mediated clustering and functional interaction of MscL channels |
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| Authors: | Grage Stephan L Keleshian Asbed M Turdzeladze Tamta Battle Andrew R Tay Wee C May Roland P Holt Stephen A Contera Sonia Antoranz Haertlein Michael Moulin Martine Pal Prithwish Rohde Paul R Forsyth V Trevor Watts Anthony Huang Kerwyn Casey Ulrich Anne S Martinac Boris |
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| Affiliation: | †Karlsruhe Institute of Technology, Institute of Biological Interfaces (IBG-2), Karlsruhe, Germany;‡DFG-Center for Functional Nanostructures, Karlsruhe, Germany;§School of Biomedical Sciences, University of Queensland, Brisbane, Australia;¶Karlsruhe Institute of Technology, Institute of Organic Chemistry, Karlsruhe, Germany;‖Victor Chang Cardiac Research Institute, Darlinghurst, Australia;††Partnership for Structural Biology, Institut Laue-Langevin, Grenoble, France;‡‡ISIS, Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot, United Kingdom;§§Department of Physics, University of Oxford, Oxford, United Kingdom;¶¶EPSAM/ISTM, Keele University, Staffordshire, United Kingdom;‖‖Biomembrane Structure Unit, Department of Biochemistry, Oxford, University of Oxford, United Kingdom;†††Department of Bioengineering, Stanford University, Stanford, California;‡‡‡St Vincent's Clinical School, University of New South Wales, Sydney, Australia |
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| Abstract: | Mechanosensitive channels allow bacteria to respond to osmotic stress by opening a nanometer-sized pore in the cellular membrane. Although the underlying mechanism has been thoroughly studied on the basis of individual channels, the behavior of channel ensembles has yet to be elucidated. This work reveals that mechanosensitive channels of large conductance (MscL) exhibit a tendency to spatially cluster, and demonstrates the functional relevance of clustering. We evaluated the spatial distribution of channels in a lipid bilayer using patch-clamp electrophysiology, fluorescence and atomic force microscopy, and neutron scattering and reflection techniques, coupled with mathematical modeling of the mechanics of a membrane crowded with proteins. The results indicate that MscL forms clusters under a wide range of conditions. MscL is closely packed within each cluster but is still active and mechanosensitive. However, the channel activity is modulated by the presence of neighboring proteins, indicating membrane-mediated protein-protein interactions. Collectively, these results suggest that MscL self-assembly into channel clusters plays an osmoregulatory functional role in the membrane. |
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