Hollow silica spheres with mesostructured shells (HSSMS) were prepared with a vesicle template of cetyltrimethylammonium bromide-sodium dodecyl sulfate-Pluronic P123 (C(16)TMAB-SDS-EO(20)PO(70)EO(20)) at a SDS/C(16)TMAB ratio of 0.6-0.8 following a fast silicification in dilute silicate solution at pH approximately 5.0. The mesostructure of the shell is disordered, and the mesopore size is about 5.5-7.5 nm. Moreover, the direction and length of the nanochannels of the shell change with the SDS/C(16)TMAB ratios. A bi-template model, in which the C(16)TMA(+)-DS(-) form the stable bilayer vesicle structure and the P123 copolymers anchored on C(16)TMA(+)-DS(-) vesicle act as the template for the mesoporous silica, was proposed to explain the formation of the HSSMS. This bi-template model can be applied extensively to prepare the HSSMS with different diameters and pore sizes by using other C(n)TMAX-SDS-EO(n)PO(m))EO(n) ternary-surfactant mixtures.

Galectins are a family of lectins that bind β-galactosides through their conserved carbohydrate recognition domain (CRD) and can induce aggregation with glycoproteins or glycolipids on the cell surface and thereby regulate cell activation, migration, adhesion, and signaling. Galectin-3 has an intrinsically disordered N-terminal domain and a canonical CRD. Unlike the other 14 known galectins in mammalian cells, which have dimeric or tandem-repeated CRDs enabling multivalency for various functions, galectin-3 is monomeric, and its functional multivalency therefore is somewhat of a mystery. Here, we used NMR spectroscopy, mutagenesis, small-angle X-ray scattering, and computational modeling to study the self-association-related multivalency of galectin-3 at the residue-specific level. We show that the disordered N-terminal domain (residues ∼20-100) interacts with itself and with a part of the CRD not involved in carbohydrate recognition (β-strands 7-9; residues ∼200-220), forming a fuzzy complex via inter- and intramolecular interactions, mainly through hydrophobicity. These fuzzy interactions are characteristic of intrinsically disordered proteins to achieve liquid-liquid phase separation, and we demonstrated that galectin-3 can also undergo liquid-liquid phase separation. We propose that galectin-3 may achieve multivalency through this multisite self-association mechanism facilitated by fuzzy interactions.

Proapoptotic BAX protein is largely cytosolic in healthy cells, but it oligomerizes and translocates to mitochondria upon receiving apoptotic stimuli. A long-standing challenge has been the inability to capture any structural information beyond the onset of activation. Here, we present solution structures of an activated BAX oligomer by means of spectroscopic and scattering methods, providing details about the monomer-monomer interfaces in the oligomer and how the oligomer is assembled from homodimers. We show that this soluble oligomer undergoes a direct conversion into membrane-inserted oligomer, which has the ability of inducing apoptosis and structurally resembles a membrane-embedded oligomer formed from BAX monomers in lipid environment. Structural differences between the soluble and the membrane-inserted oligomers are manifested in the C-terminal helices. Our data suggest an alternative pathway of apoptosis in which BAX oligomer formation occurs prior to membrane insertion.

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