Clustering and Functional Interaction of MscL Channels

Abstract

Mechanosensitive channels allow bacteria to respond to osmotic stress by opening a nanometer size pore in the cellular membrane. While the underlying mechanism has been studied intensively on the basis of individual channels, the work described here sheds light on the behavior of an ensemble of mechanosensitive channels of large conductance (MscL) in the membrane. Evaluating the spatial distribution of MscL channels in the bilayer using patch clamp, fluorescence, neutron scattering and reflection techniques, as well as atomic force microscopy and mathematical modeling, MscL was found to form clusters under a wide range of conditions. Within the cluster, MscL is closely packed, but still active and mechanosensitive. The channel activity, however, is modulated by the presence of neighbouring proteins, indicating functional protein-protein interactions. Collectively, the results demonstrate a potential functional role for self-assembly of MscL in the membrane.Supported by the grants from the Australian Research Council and the National Health and Medical Research Council of Australia, DFG Centre for Functional Nanostructures (project E3.4), Engineering and Physical Sciences Research Council (EPSRC) and European Union.