Cardiolipin Effects on the Gating Behaviour and Reconstitution of MscL and MscS

Abstract

The mechanosensitive channels of large (MscL) and small (MscS) conductance act as osmosensors in bacterial cells against hypo-osmotic shock. MscL has been extensively studied by reconstitution into liposomes2,3, however MscS has proved more difficult to reconstitute, requiring high protein-lipid ratios4,5. We recently published an improved reconstitution method for both MscL and MscS in soy azolectin6, a mixture that contains lipids, sugars and sterols. We have expanded these results and show here the effect of both individual and mixtures of lipids on the reconstitution and channel gating behaviour of co-reconstituted MscL and MscS. Introduction of the highly charged lipid cardiolipin causes rapid gating of MscS (Fig 1A) in comparison to soy azolectin (Fig 1B), indicating that lipid charge may play a significant role on channel gating dynamics.View Large Image | View Hi-Res Image | Download PowerPoint SlideFig 1 (A) MscS/MscL co- reconstitution in soy azolectin. (B) MscS/MscL co- reconstitution in mixture of phosphatidyl ethanolamine/ phosphatidyl choline/cardiolipin at a wt/wt ratio of 7:2:1, recordings at a pipette voltage of +30 mV.Supported by the Australian Research Council and the National Health and Medical Research Council of Australia.