Functional convergence of hopanoids and sterols in membrane ordering.
Liquid-ordered phases are one of two biochemically active membrane states, which until now were thought to be a unique consequence of the interactions between eukaryotic membrane lipids. The formation of a liquid-ordered phase depends crucially on the ordering properties of sterols. However, it is not known whether this capacity exists in organisms that lack sterols, such as bacteria. We show that diplopterol, the simplest bacterial hopanoid, has similar properties and that hopanoids are bacterial "sterol surrogates" with the ability to order saturated lipids and to form a liquid-ordered phase in model membranes. These observations suggest that the evolution of an ordered biochemically active liquid membrane could have evolved before the oxygenation of Earth's surface and the emergence of sterols.
Max Plank Institute for Molecular Cell Biology and Genetics, 01307 Dresden,  Germany.
James Peter
JP
Sáenz
Erdinc
E
Sezgin
Petra
P
Schwille
Kai
K
Simons
D001419:Bacteria / Q000378:metabolism / Q000648:ultrastructure; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002784:Cholesterol / Q000737:chemistry* / Q000378:metabolism; D019143:Evolution, Molecular; D008050:Lipid A / Q000737:chemistry / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism*; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D008956:Models, Chemical; D013109:Sphingomyelins / Q000737:chemistry / Q000378:metabolism; D013261:Sterols / Q000737:chemistry* / Q000378:metabolism; D013729:Terpenes / Q000737:chemistry / Q000378:metabolism; D014315:Triterpenes / Q000737:chemistry* / Q000378:metabolism
D008050:Lipid A; D008051:Lipid Bilayers; D008081:Liposomes; D008563:Membrane Lipids; D013109:Sphingomyelins; D013261:Sterols; D013729:Terpenes; D014315:Triterpenes; C029766:diplopterol; D002784:Cholesterol