Melting transitions in biomembranes

TY - JOUR

T1 - Melting transitions in biomembranes

AU - Muzic, Tea

AU - Tounsi, Fatma

AU - Madsen, Soren B.

AU - Pollakowski, Denis

AU - Konrad, Manfred

AU - Heimburg, Thomas

PY - 2019/11/1

Y1 - 2019/11/1

N2 - We investigated melting transitions in native biological membranes containing their membrane proteins. The membranes originated from E. coli, B. subtilis, lung surfactant and nerve tissue from the spinal cord of several mammals. For some preparations, we studied the pressure, pH and ionic strength dependence of the transition. For porcine spine, we compared the transition of the native membrane to that of the extracted lipids. All preparations displayed melting transitions of 10–20° below physiological or growth temperature, independent of the organism of origin and the respective cell type. We found that the position of the transitions in E. coli membranes depends on the growth temperature. We discuss these findings in the context of the thermodynamic theory of membrane fluctuations close to transition that predicts largely altered elastic constants, an increase in fluctuation lifetime and in membrane permeability. We also discuss how to distinguish lipid melting from protein unfolding transitions. Since the feature of a transition slightly below physiological temperature is conserved even when growth conditions change, we conclude that the transitions are likely to be of major biological importance for the survival and the function of the cell.

AB - We investigated melting transitions in native biological membranes containing their membrane proteins. The membranes originated from E. coli, B. subtilis, lung surfactant and nerve tissue from the spinal cord of several mammals. For some preparations, we studied the pressure, pH and ionic strength dependence of the transition. For porcine spine, we compared the transition of the native membrane to that of the extracted lipids. All preparations displayed melting transitions of 10–20° below physiological or growth temperature, independent of the organism of origin and the respective cell type. We found that the position of the transitions in E. coli membranes depends on the growth temperature. We discuss these findings in the context of the thermodynamic theory of membrane fluctuations close to transition that predicts largely altered elastic constants, an increase in fluctuation lifetime and in membrane permeability. We also discuss how to distinguish lipid melting from protein unfolding transitions. Since the feature of a transition slightly below physiological temperature is conserved even when growth conditions change, we conclude that the transitions are likely to be of major biological importance for the survival and the function of the cell.

KW - Thermodynamics

KW - Elastic constants

KW - Ions

KW - E. coli

KW - B. subtilis

KW - Lung surfactant

KW - Nerves

U2 - 10.1016/j.bbamem.2019.07.014

DO - 10.1016/j.bbamem.2019.07.014

M3 - Journal article

C2 - 31465764

SN - 0005-2736

VL - 1861

JO - B B A - Biomembranes

JF - B B A - Biomembranes

IS - 11

M1 - 183026

ER -