TABLE 1.
A summary of the structural and functional characteristics of the most studied natural NVPNs. The indicated code corresponds to the respective PDB ID.
| Protein nanocages | Structural characteristics | Functional characteristics | References | ||||
|---|---|---|---|---|---|---|---|
| Number of monomers | Molecular weight | Geometry | Dimensions a | Native organism | Biological function | ||
| Vault (4V60, Figure 1A) | 78–96 | 13 MDa | Dihedral (39-fold)–Barrel-like structure | OL: 75 nm; OW: 42 nm | Eukarya (Example: Rattus norvegicus) | Involved in intracellular transport, cell signalling, cell survival and innate immunity | Kong et al. (1999), Poderycki et al. (2006), Anderson et al. (2007), Tanaka et al. (2009) |
| Aminopeptidase (PepA) (3KL9, Figure 1B) | 12 | 457 kDa | Tetrahedral | OD: 12 nm; ID: 6 nm | Streptococcus pneumonia | Hydrolysis of oligopeptides into free amino acids | Kim et al. (2010), San et al. (2011), SIB Swiss Institute of Bioinformatics (2023) |
| DNA-binding protein from starved cells (Dps) (1QGH, Figure 1C) | 12 | 216 kDa | Tetrahedral | OD: 9 nm; ID: 5 nm | Listeria innocua | Prevention of oxidative damage of DNA | Ilari et al. (2000), Kang et al. (2008), Haikarainen and Papageorgiou (2010) |
| Ferritin (2FHA, Figure 1D) | 24 | 509 kDa | Octahedral | OD: 12 nm; ID: 8 nm | Homo sapiens | Regulation of the storage and release of iron | Zhang and Orner (2011), He and Marles-Wright (2015), SIB Swiss Institute of Bioinformatics (2023) |
| Heat shock protein (HSP) (1SHS, Figure 1E) | 24 | 396 kDa | Octahedral | OD: 12 nm; ID: 6.5 nm | Methanococcus jannaschii | Chaperone activity in response to cellular stress | Kim et al. (1998a), Kim R. et al. (1998), Kim et al. (2003), Bova et al. (2002), Flenniken et al. (2003) |
| Dihydrolipoyl acetyltransferase (E2) (1B5S, Figure 1F) | 60 | 1.6 MDa | Icosahedral | OD: 24 nm; ID: n.a | Bacillus stearothermophilus | Component of the pyruvate dehydrogenase (PDH) multienzyme complex | Domingo et al. (2001), Milne et al. (2006), Dalmau et al. (2008), SIB Swiss Institute of Bioinformatics (2023) |
| Encapsulin (3DKT, Figure 1G) | 60 | 1.9 MDa | Icosahedral | OD: 24 nm; ID: 20 nm | Thermotoga maritima | Involved indirectly in oxidative stress responses through the encapsulation of other related proteins | Sutter et al. (2008), Tamura et al. (2015), Cassidy-Amstutz et al. (2016), Giessen (2016) |
| Lumazine synthase (1RVV or 1HQK, Figure 1H) | 60 | 1 MDa | Icosahedral | OD: 14.7 nm; ID: 7.8 nm | Bacillus subtilis, Aquifex aeolicus | Enzyme complex involved in the synthesis of lumazine (riboflavin precursor) | Ritsert et al. (1995), Zhang et al. (2001), Ladenstein et al. (2013) |
a
OL, outer length; OW, outer width; OD, outer diameter; ID, inner diameter; n.a, not available.