Designed, Programmable Protein Cages Utilizing Diverse Metal Coordination Geometries Show Reversible, pH-Dependent Assembly.

The rational design and production of a novel series of engineered protein cages are presented, which have emerged as versatile and adaptable platforms with significant applications in biomedicine. These protein cages are assembled from multiple protein subunits, and precise control over their interactions is crucial for regulating assembly and disassembly, such as the on-demand release of encapsulated therapeutic agents. This approach employs a homo-undecameric, ring-shaped protein scaffold with strategically positioned metal binding sites.

Structural basis of chiral wrap and T-segment capture by DNA gyrase.

Type II topoisomerase DNA gyrase transduces the energy of ATP hydrolysis into the negative supercoiling of DNA. The postulated catalytic mechanism involves stabilization of a chiral DNA loop followed by the passage of the T-segment through the temporarily cleaved G-segment resulting in sign inversion. The molecular basis for this is poorly understood as the chiral loop has never been directly observed.

Reengineering of an Artificial Protein Cage for Efficient Packaging of Active Enzymes.

Protein cages that readily encapsulate active enzymes of interest present useful nanotools for delivery and catalysis, wherein those with programmable disassembly characteristics serve as particularly attractive platforms. Here, a general guest packaging system based on an artificial protein cage, TRAP-cage, the disassembly of which can be induced by the addition of reducing agents, is established. In this system, TRAP-cage with SpyCatcher moieties in the lumen is prepared using genetic modification of the protein building block and assembled into a cage structure with either monovalent gold ions or molecular crosslinkers.

Virus-like particles derived from bacteriophage MS2 as antigen scaffolds and RNA protective shells.

The versatile potential of bacteriophage MS2-derived virus-like particles (VLPs) in medical biotechnology has been extensively studied during the last 30 years. Since the first reports showing that MS2 VLPs can be produced at high yield and relatively easily engineered, numerous applications have been proposed. Particular effort has been spent in developing MS2 VLPs as protective capsules and delivery platforms for diverse molecules, such as chemical compounds, proteins and nucleic acids.