title: Bilayer-mediated clustering and functional interaction of MscL channels.
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.
authors.affiliation: Karlsruhe Institute of Technology, Institute of Biological Interfaces (IBG-2), Karlsruhe, Germany.
authors.forename: Stephan L
authors.initials: SL
authors.lastname: Grage
authors.forename: Asbed M
authors.initials: AM
authors.lastname: Keleshian
authors.forename: Tamta
authors.initials: T
authors.lastname: Turdzeladze
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Battle
authors.forename: Wee C
authors.initials: WC
authors.lastname: Tay
authors.forename: Roland P
authors.initials: RP
authors.lastname: May
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Holt
authors.forename: Sonia Antoranz
authors.initials: SA
authors.lastname: Contera
authors.forename: Michael
authors.initials: M
authors.lastname: Haertlein
authors.forename: Martine
authors.initials: M
authors.lastname: Moulin
authors.forename: Prithwish
authors.initials: P
authors.lastname: Pal
authors.forename: Paul R
authors.initials: PR
authors.lastname: Rohde
authors.forename: V Trevor
authors.initials: VT
authors.lastname: Forsyth
authors.forename: Anthony
authors.initials: A
authors.lastname: Watts
authors.forename: Kerwyn Casey
authors.initials: KC
authors.lastname: Huang
authors.forename: Anne S
authors.initials: AS
authors.lastname: Ulrich
authors.forename: Boris
authors.initials: B
authors.lastname: Martinac
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D007473:Ion Channels / Q000737:chemistry* / Q000378:metabolism*; D008051:Lipid Bilayers / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D018625:Microscopy, Atomic Force; D033363:Neutron Diffraction; D011485:Protein Binding; D053838:Scattering, Small Angle
chemical_list: D029968:Escherichia coli Proteins; D007473:Ion Channels; D008051:Lipid Bilayers; D008081:Liposomes; C086596:MscL protein, E coli