Related Experiment Videos
Structure and polymorphism of bipolar isopranyl ether lipids from archaebacteria
Journal of Molecular Biology
|March 5, 1985
Summary
Archaebacterial lipids from Sulfolobus solfataricus exhibit diverse structures and phases under physiological conditions. Their unique biphytanyl chains and headgroup arrangements influence membrane properties and stability.
Area of Science:
- Biochemistry
- Structural Biology
- Extremophile Biology
Background:
- Sulfolobus solfataricus, an extremophile, possesses unique ether-linked lipids distinct from eukaryotic and prokaryotic fatty acid lipids.
- These lipids are composed of C40 omega-omega' biphytanyl residues and glycerol or nonitol headgroups.
Purpose of the Study:
- To elucidate the structure and polymorphism of lipids extracted from Sulfolobus solfataricus.
- To investigate the influence of water content and temperature on lipid phase behavior.
- To understand the physiological implications of lipid structure and organization.
Main Methods:
- X-ray scattering techniques were employed to study four lipid preparations: total lipid extract, polar lipid extract, symmetric glycerol dialkyl glycerol tetraether, and asymmetric glycerol dialkyl nonitol tetraether.
- Experiments were conducted across a range of water content and temperatures.
Main Results:
- A wide variety of lipid phases were observed under near-physiological conditions, indicating significant polymorphism.
- Two chain conformations were identified: a disordered (alpha) phase at high temperatures and an ordered (beta') phase at lower temperatures. The alpha conformation prevails under cellular conditions.
- Unsubstituted glycerol headgroups segregated within the hydrocarbon matrix in alpha-conformation phases, potentially enabling lipid chains to span large hydrocarbon gaps.
- Two cubic phases in total and polar lipid extracts exhibited unusual metastability, attributed to the intertwined 3D networks and hindered molecular diffusion.
Conclusions:
- The observed lipid polymorphism is likely a fundamental property related to their physiological role in extremophiles.
- The unique structural features, including headgroup segregation and biphytanyl chain entanglement, contribute to membrane stability and function in extreme environments.
- The metastability of cubic phases suggests a complex interplay between lipid structure and phase behavior, offering insights into membrane dynamics.