Bacterial Tetraethers

Tetraether monosaccharide phospholipids (MPL) are the main phospholipids of Thermoplasma acidophilum. They contain a glycerophosphate and a gulosyl pyranoside monosaccharide linked via a tetraether chain. The MPL is largely responsible for T. acidophilum’s ability to survive in low pH (1-2) and high temperatures (55-59°C)1 and constitutes almost half of its total lipids.2 MPL is useful for making liposomes to study various molecular functions.3 It has been found to be valuable in the development and application of model membrane systems on the basis of tetraether lipids. Examples include the integral membrane protein alamethicin and the peripheral proteins melittin, valinomycin, and nonactin that interact primarily with lipid head groups and are readily incorporated into the tetraether lipid structures. Growth of various living cell types was not affected by exposure to MPL and when MPL liposomes were injected into mice no pharmacological or toxic effects were detected other than increased behavioral activity. Labeled MPL liposomes were found to be rapidly cleared from the circulation.4

References:

1. H. Shimada et al. “Complete Polar Lipid Composition of Thermoplasma acidophilum HO-62 Determined by High-Performance Liquid Chromatography with Evaporative Light-Scattering Detection” Journal of Bacteriology, Vol. 184:2 pp. 556-563, 2002
2. I. Uda et al. “Characterization of caldarchaetidylglycerol analogs, dialkyl-type and trialkyl-type, from Thermoplasma acidophilum” Lipids, Vol. 35:10 pp. 1155-1157, 2000
3. H.-J. Freisleben et al. “Reconstitution of bacteriorhodopsin and ATP synthase from Micrococcus luteus into liposomes of the purified main tetraether lipid from Thermoplasma acidophilum : proton conductance and light-driven ATP synthesis” Chemistry and Physics of Lipids, Vol. 78:2 pp. 137, 1995
4. H.-J. Freisleben et al. “Toxicity and Biodistribution of Liposomes of the Main Phospholipid from the Archaebacterium Thermoplasma Acidophilum in Mice” Journal of Liposome Research, Vol. 5:1 pp. 215, 1995