Discoid Bicelles as Efficient Templates for Pillared Lamellar Periodic Mesoporous Silicas at pH 7 and Ultrafast Reaction Times

We report the first synthesis of periodic mesoporous silicas templated by bicelles. The obtained materials form novel pillared lamellar structures with a high degree of periodic order, narrow pore size distributions, and exceptionally high surface areas

Probing the Caveolin-1 P132L Mutant: Critical Insights into Its Oligomeric Behavior and Structure

Caveolin-1 is the most important protein found in caveolae, which are cell surface invaginations of the plasma membrane that act as signaling platforms. A single point mutation in the transmembrane domain of caveolin-1 (proline 132 to leucine) has deleterious effects on caveolae formation <i>in vivo</i> and has been implicated in various disease states, particularly aggressive breast cancers. Using a combination of gel filtration chromatography and analytical ultracentrifugation, we found that a fully functional construct of caveolin-1 (Cav1_62–178) was a monomer in dodecylphosphocholine micelles. In contrast, the P132L mutant of Cav1_62–178 was dimeric. To explore the dimerization of the P132L mutant further, various truncated constructs (Cav1_82–178, Cav1_96–178, Cav1_62–136, Cav1_82–136, Cav1_96–136) were prepared which revealed that oligomerization occurs in the transmembrane domain (residues 96–136) of caveolin-1. To characterize the mutant structurally, solution-state NMR experiments in <i>lyso</i>-myristoylphosphatidylglycerol were undertaken of the Cav1_96–136 P132L mutant. Chemical shift analysis revealed that, compared to the wild-type, helix 2 in the transmembrane domain was lengthened by four residues (wild-type, residues 111–129; mutant, residues 111–133), which corresponds to an extra turn in helix 2 of the mutant. Lastly, point mutations at position 132 of Cav1_62–178 (P132A, P132I, P132V, P132G, P132W, P132F) revealed that no other hydrophobic amino acid can preserve the monomeric state of Cav1_62–178, which indicates that proline 132 is critical in supporting proper caveolin-1 behavior

Low‑<i>q</i> Bicelles Are Mixed Micelles

Bicelles are used in many membrane protein studies because they are thought to be more bilayer-like than micelles. We investigated the properties of “isotropic” bicelles by small-angle neutron scattering, small-angle X-ray scattering, fluorescence anisotropy, and molecular dynamics. All data suggest that bicelles with a <i>q</i> value below 1 deviate from the classic bicelle that contains lipids in the core and detergent in the rim. Thus not all isotropic bicelles are bilayer-like