Professor Boris Martinac
Department of Pharmacology
The University of Western Australia
Nedlands, Australia

Monday, October 30, 2000
3:00 pm (CT)
3269 Beckman Institute

Abstract

The property of bacterial mechanosensitive (MS) ion channels of being activated by mechanical force, transmitted via the lipid bilayer alone, allowed for detergent solubilization and functional reconstitution of these channels into artificial liposomes amenable to patch-clamp recording. This channel property made further possible the identification of a membrane protein underlying the activity of MscL, the MS channel of large conductance firstly described in Escherichia coli. The MscL protein was partially sequenced, which enabled the cloning of the corresonding mscL gene followed by the determination of the MscL tertiary structure. A 3D x-ray crystallographic study solved the oligomeric structure of the MscL and indicated that it was organized as a homopentamer. Despite the available 3D MscL structure of the closed channel, the molecular mechanism of how mechanical force may gate this MS channel remains unresolved at present. Several models of the MscL gating by mechanical force will be discussed including recent results demonstrating the role of the hydrophobic mismatch in MscL mechanosensitivity.

Tea and coffee will be served in R3151 Beckman Institute at 2:15pm.