Structural highlights
Function
[P1_BPPH6] P1 is the major inner capsid (core) protein of the polyhedral procapsid, which is responsible for genomic replication and transcription. Forms a dodecahedral shell from 60 asymmetric dimers. Binds to RNA and may be involved in genomic packaging. [CAPSD_BPPH6] Assembles to form an icosahedral capsid with a T=13 symmetry. Drives the penetration of the inner capsid (core) into the cytoplasm.[1] [2] [P4_BPPH6] P4 is one of the structural proteins of the polyhedral procapsid, which is responsible for genomic replication and transcription. Displays single-stranded RNA-stimulated NTPase activity.[3]
Publication Abstract from PubMed
Correct outer protein shell assembly is a prerequisite for virion infectivity in many multi-shelled dsRNA viruses. In the prototypic dsRNA bacteriophage phi6, the assembly reaction is promoted by calcium ions but its biomechanics remain poorly understood. Here, we describe the near-atomic resolution structure of the phi6 double-shelled particle. The outer T=13 shell protein P8 consists of two alpha-helical domains joined by a linker, which allows the trimer to adopt either a closed or an open conformation. The trimers in an open conformation swap domains with each other. Our observations allow us to propose a mechanistic model for calcium concentration regulated outer shell assembly. Furthermore, the structure provides a prime exemplar of bona fide domain-swapping. This leads us to extend the theory of domain-swapping from the level of monomeric subunits and multimers to closed spherical shells, and to hypothesize a mechanism by which closed protein shells may arise in evolution.
Double-stranded RNA virus outer shell assembly by bona fide domain-swapping.,Sun Z, El Omari K, Sun X, Ilca SL, Kotecha A, Stuart DI, Poranen MM, Huiskonen JT Nat Commun. 2017 Mar 13;8:14814. doi: 10.1038/ncomms14814. PMID:28287099[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Poranen MM, Daugelavicius R, Ojala PM, Hess MW, Bamford DH. A novel virus-host cell membrane interaction. Membrane voltage-dependent endocytic-like entry of bacteriophage straight phi6 nucleocapsid. J Cell Biol. 1999 Nov 1;147(3):671-82. PMID:10545509
- ↑ Jaalinoja HT, Huiskonen JT, Butcher SJ. Electron cryomicroscopy comparison of the architectures of the enveloped bacteriophages phi6 and phi8. Structure. 2007 Feb;15(2):157-67. PMID:17292834 doi:http://dx.doi.org/S0969-2126(07)00026-3
- ↑ Pirttimaa MJ, Paatero AO, Frilander MJ, Bamford DH. Nonspecific nucleoside triphosphatase P4 of double-stranded RNA bacteriophage phi6 is required for single-stranded RNA packaging and transcription. J Virol. 2002 Oct;76(20):10122-7. PMID:12239286
- ↑ Sun Z, El Omari K, Sun X, Ilca SL, Kotecha A, Stuart DI, Poranen MM, Huiskonen JT. Double-stranded RNA virus outer shell assembly by bona fide domain-swapping. Nat Commun. 2017 Mar 13;8:14814. doi: 10.1038/ncomms14814. PMID:28287099 doi:http://dx.doi.org/10.1038/ncomms14814
