Symmetry disruption commits vault particles to disassembly

Abstract

Vaults are ubiquitous ribonucleoprotein particles involved in a diversity of cellular processes, with promising applications as nanodevices for delivery of multiple cargos. The vault shell is assembled by the symmetrical association of multiple copies of the major vault protein that, initially, generates half vaults. The pairwise, anti-parallel association of two half vaults produces whole vaults. Here, using a combination of vault recombinant reconstitution and structural techniques, we characterized the molecular determinants for the vault opening process. This process commences with a relaxation of the vault waist, causing the expansion of the inner cavity. Then, local disengagement of amino-terminal domains at the vault midsection seeds a conformational change that leads to the aperture, facilitating access to the inner cavity where cargo is hosted. These results inform a hitherto uncharacterized step of the vault cycle and will aid current engineering efforts leveraging vault for tailored cargo delivery.

Hallucinating symmetric protein assemblies

“…3J and table S2). The high structural symmetry of these designed complexes rivals that of natural proteins—the highest cyclic symmetry recorded in the PDB for naturally occurring proteins is C39 [vault proteins ( 36 ), PDB IDs 4HL8 and 7PKY].…”

“…HALC3–33_343 has an unusual internal loop region breaking the outer helices midway in the repeat, producing a widening of the ring on one side, which is clearly visible in the cryoEM reconstruction; the protomer has a low TM-score (0.48) despite having an LRR-like topology, and the oligomer is even further from anything currently known (TM-score: 0.41, Fig. 4J , Table S2 ) The high structural symmetry of these designed complexes rivals that of natural proteins: the highest cyclic symmetry recorded in the PDB for naturally occurring proteins is C39 (Vault proteins ( 35 ), PDB 4HL8 and 7PKY), and there are no closed symmetric α/β ring-like structures.…”

Hallucinating protein assemblies

“…4H-I). HALC3-33_343 has an unusual internal loop region breaking the outer helices midway in the repeat, producing a widening of the ring on one side, which is clearly visible in the cryoEM reconstruction; the protomer has a low TM-score (0.48) despite having an LRR-like topology, and the oligomer is even further from anything currently known (TM-score: 0.41) To our knowledge, these designs are the largest cyclic homo-oligomers designed de novo to date, and the sophistication of the fold, topology, and high sequence and structural symmetry rivals that in nature: the highest cyclic symmetry recorded in the PDB for naturally occurring proteins is C39 (Vault proteins ( 32 ), PDB 4HL8 and 7PKY), and there are no closed symmetric α/β ring-like structures.…”

Tailored Functionalized Protein Nanocarriers for Cancer Therapy: Recent Developments and Prospects

“…In native vaults, three proteins are present in multiple copies: vault poly(ADP-ribose) polymerase (193 kDa, VPARP), vault telomerase-associated protein (290 kDa, TEP1), and major vault protein (100 kDa, MVP) [ 56 ]. The most recent approaches for recombinant vault production only exploit genetically expressed MVP because it accounts for 75% of the natural vault protein mass and is adequate to create vault nanoparticles [ 57 ]. Vault particles are promising therapeutic nanocarriers for bioactive drug encapsulation owing to their unique properties, such as self-assembled proteinaceous nanostructures with a large internal volume (5 × 10 4 nm 3 ) [ 29 ].…”

“…Vault proteins are biomedically useful because of their non-immunogenicity and structural stability [ 57 ]. Accordingly, these proteins are used as precise nanocarriers for the delivery of several immunogenic proteins, drugs, and other biomolecules ( Table 1 ) [ 59 ].…”