Mobility and temperature resistance of trehalose mycolates as key characteristics of the outer membrane of Mycobacterium tuberculosis

Abstract

Trehalose mycolates are fundamental characteristics of the outer membrane (mycomembrane) of Mycobacterium tuberculosis and they are supposed to play a key role in the low permeability and high resistance of mycobacteria to many antibiotics; however, still, the molecular characteristics making mycolates so effective in their biological function are not fully understood. This work aims to investigate by quasi-elastic neutron scattering the diffusive dynamical properties of trehalose mycolates in water mixtures as a function of temperature, energy and exchanged wavevector Q in order to elucidate the dynamics–function relation in the mycomembrane. A comparison with lecithin lipids in water mixtures is performed since they are considered among the most rigid and resistant lipids. From the analysis of the data collected as a function of temperature, a lower temperature dependence of the mobility as well as a higher rigidity of trehalose mycolates in comparison with lecithin lipids are highlighted. The present findings provide detailed molecular information which allows to go ahead in the understanding at a molecular level of the resistance to stress and antibiotics by corynebacteria and mycobacteria.

Keywords:

• Mycobacterium tuberculosis
• trehalose mycolates
• diffusion
• stability
• quasi elastic neutron scattering

Acknowledgements

The authors gratefully acknowledge the ISIS facility (STFC, RAL, Chilton, UK) for dedicated runs at the OSIRIS and IRIS spectrometers. Federica Migliardo gratefully acknowledges the European Molecular Biology Organisation (EMBO) for the short-term fellowship “Role of trehalose in the structure, permeability and stability of mycomembranes in Mycobacterium tuberculosis and Corynebacterium glutamicum” [ASTF 502 – 2011].