CRAFTing Delivery of Membrane Proteins into Protocells using Nanodiscs.

For the successful generative engineering of functional artificial cells, a convenient and controllable means of delivering membrane proteins into membrane lipid bilayers is necessary. Here we report a delivery system that achieves this by employing membrane protein-carrying nanodiscs and the calcium-dependent fusion of phosphatidylserine lipid membranes. We show that lipid nanodiscs can fuse a transported lipid bilayer with the lipid bilayers of small unilamellar vesicles (SUVs) or giant unilamellar vesicles (GUVs) while avoiding recipient vesicles aggregation.

A bacteriophage mimic of the bacterial nucleoid-associated protein Fis.

We report the identification and characterization of a bacteriophage λ-encoded protein, NinH. Sequence homology suggests similarity between NinH and Fis, a bacterial nucleoid-associated protein (NAP) involved in numerous DNA topology manipulations, including chromosome condensation, transcriptional regulation and phage site-specific recombination. We find that NinH functions as a homodimer and is able to bind and bend double-stranded DNA in vitro.

Conformational variability of goat β-lactoglobulin: crystallographic and thermodynamic studies.

Goat β-lactoglobulin (GLG), lipocalin protein sharing high sequence similarity to bovine β-lactoglobulin (BLG), has been structurally and thermodynamically characterized. Two crystal forms of GLG have been obtained, trigonal (P3121) and orthorhombic (P21212), with unique molecular packing, not observed previously for BLG. In the trigonal structure, GLG molecules have EF-loop in closed conformation while in the orthorhombic structure, for the first time, symmetric and asymmetric dimers of β-lactoglobulin are observed simultaneously.

Structure of two crystal forms of sheep β-lactoglobulin with EF-loop in closed conformation.

Ovine β-lactoglobulin has been isolated from whey fraction of sheep milk and crystallized. The high-resolution structures of two crystal forms (triclinic and trigonal) obtained at pH 7.0 have been determined revealing that ovine protein, similarly to its bovine analog, is dimeric.

The differences in binding 12-carbon aliphatic ligands by bovine β-lactoglobulin isoform A and B studied by isothermal titration calorimetry and X-ray crystallography.

Isoforms A (LGB-A) and B (LGB-B) of bovine lactoglobulin, the milk protein, differ in positions 64 (D↔G) and 118 (V↔A). Interactions of LGB-A and LGB-B with sodium dodecyl sulfate (SDS), dodecyltrimethylammonium chloride (DTAC) and lauric acid (LA), 12-carbon ligands possessing differently charged polar groups, were investigated using isothermal titration calorimetry and X-ray crystallography, to study the proton linkage phenomenon and to distinguish between effects related to different isoforms and different ligand properties. The determined values of ΔS and ΔH revealed that for all ligands, binding is entropically driven.