Cholesterol and ergosterol are two dominant sterols in the membranes of eukaryotic and yeast cells, respectively. Although their chemical structure is very similar, their impact on the structure and dynamics of membranes differs. In this work, we have explored the effect of these two sterols on binary mixtures with  1, 2-dipalnitoyl-sn-glycerol-3-phosphocholine (DPPC) lipid bilayer at various sterol concentration and temperatures , employing molecular dynamics simulations. The simulations revealed that cholesterol has a stronger impact on the ordering of the lipid chains and leads to more condensed membranes with respect to ergosterol. This difference likely arises from a more planar structure of the ring part as well as the better alignment of cholesterol among the DPPC chains with respect to ergosterol. The degree of the planarity of the ring system affects the orientation of the methyl groups on the rough side and distribute the lipid chains on the two sides of the sterols differently. Similar to the structural observations, cholesterol also has a stronger influence on the dynamics, and consistently, establishes stronger DPPC-sterol interactions when compared to ergosterol. Although our findings are consistent with some previous simulations as well as recent experiments, they are at odds with some other studies. Therefore, the presented results may shed new lights on the impact of sterols on the saturated lipids bilayers with implications for binary mixtures of lipids as well as lipid rafts .
Sterols have been ascribed a major role in URLanization of biological membranes, in particular for the formation of liquid ordered domains in complex lipid mixtures. Interestingly, evolution has resulted in a preference for chemically similar but distinct sterol types - with cholesterol the major sterol of mammalian cells and ergosterol dominating in membranes of fungal cells. However, the molecular basis and functional consequences of the choice in sterols are not well understood. Here, we employed molecular dynamics simulations to compare the effects of cholesterol and ergosterol on binary mixtures with saturated 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) lipids. Our simulations with varying sterol concentrations and temperatures revealed that while both sterols were able to induce the formation of liquid ordered membrane domains, cholesterol had a noticeably stronger impact on lipids condensing and ordering. The observed differences could be attributed to the higher planarity of the cholesterol ring region. This planarity combined with an inherent asymmetry in its molecular interactions led to better alignment and hence stronger interaction with saturated acyl chains. Our results show that ergosterol does not have an increased capacity to form ordered lipid domains compared to cholesterol and indicate that the high order demonstrated for fungal plasma membranes must therefore be generated via different mechanisms .
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Cholesterol and ergosterol are two dominant sterols in the membranes of eukaryotic and yeast cells, respectively. Although their chemical structure is very similar, their impact on the structure and dynamics of membranes differs. In this work, we have explored the effect of these two sterols
Sterols have been ascribed a major role in URLanization of biological membranes, in particular for the formation of liquid ordered domains in complex lipid mixtures. Interestingly, evolution has resulted in a preference for chemically similar but distinct sterol types - with cholesterol the major sterol of mammalian cells and ergosterol dominating in membranes of fungal cells. However, the molecular basis and functional consequences of the choice in sterols are not well understood. Here, we employed molecular dynamics simulations to compare the effects of cholesterol and ergosterol
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saturated
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2-dipalnitoyl-sn-glycerol-3-phosphocholine
2-dipalmitoyl-sn-glycero-3-phosphocholine
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lipid bilayer at various sterol concentration and temperatures , employing molecular dynamics simulations. The simulations revealed that cholesterol has a
lipids. Our simulations with varying sterol concentrations and temperatures revealed that while both sterols were able to induce the formation of liquid ordered membrane domains, cholesterol had a noticeably
R
the ordering of the lipid chains and leads to more condensed membranes with respect to ergosterol. This difference likely arises from a more planar structure of the ring part as well as the better alignment of cholesterol among the DPPC chains with respect to ergosterol. The degree of the
lipids condensing and ordering. The observed differences could be attributed to the higher
R
ring system affects the orientation of the methyl groups on the rough side and distribute the lipid chains on the two sides of the sterols differently. Similar to the structural observations, cholesterol also has a stronger influence on the dynamics, and consistently, establishes stronger DPPC-sterol interactions when compared to ergosterol. Although our findings are consistent with some previous simulations as well as recent experiments, they are at odds with some other studies. Therefore, the presented results may shed new lights on the impact of sterols on the saturated lipids bilayers with implications for binary mixtures of lipids as well as lipid rafts
cholesterol ring region. This planarity combined with an inherent asymmetry in its molecular interactions led to better alignment and hence stronger interaction with saturated acyl chains. Our results show that ergosterol does not have an increased capacity to form ordered lipid domains compared to cholesterol and indicate that the high order demonstrated for fungal plasma membranes must therefore be generated via different mechanisms