Enterobacteriophage Qbeta
| Enterobacteriophage Qbeta | ||||||||||||||||||
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TEM image of phage Qβ |
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| Escherichia virus Qbeta | ||||||||||||||||||
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The Enterobacteriophage Qbeta (official Escherichia Qbeta virus , outdated bacteriophage QB , coliphage QB ) having a single-stranded linear RNA - genome , which in an icosahedral capsid is packaged nm with a diameter of 25th Its host is the bacterium Escherichia coli (Colibacterium). Qβ enters its host cell after binding to the side of an F-pilus (sex pilus ).
Genome
The genome of Qβ is 4215 nucleotides long. It has three open reading frames (ORFs) and codes for four proteins : A1, A2, CP and qβ (- replicase ). The genome is strongly structured, which on the one hand regulates gene expression and on the other hand protects the genome from destructive RNases of the host cell.
Protein A2
A2 is called a maturation protein because of its lysis activity. There is one copy of A2 per virus particle (virion). The mechanism of lysis is similar to that of penicillin ; A2 inhibits the formation of peptidoglycan by inhibiting the enzyme UDP-N-acetylglucosamine-1-carboxyvinyltransferase (MurA), which catalyzes the first step in peptidoglycan synthesis.
A2 also works in host cell recognition and penetration into the host cell. When A2 binds to the bacterium's sex pilus, A2 splits and clears a path by creating a pore in the host's cell wall.
RNA polymerase
The RNA polymerase, which replicates both the plus and minus strands of RNA, is a complex of four proteins: the beta subunit (qβ replicase) is encoded by the phage itself, while the other three subunits are encoded by the bacterial genome become: the alpha subunit ( ribosomal protein S1), the gamma subunit ( elongation factor Tu, EF-Tu ) and the delta subunit (elongation factor Ts, EF-Ts ).
use
RNA from bacteriophage Qβ was used by Sol Spiegelman in experiments that evolutionarily favored faster replication and thus shorter RNA strands. In the end, Spiegelman's monster formed , a self-replicating RNA chain of only 218 nucleotides.
In March 2020, attempts by the Forschungsverbund Berlin to develop antibodies against influenza and coronaviruses (such as the cause of the Covid-19 pandemic , SARS-CoV-2 ) with the help of modified empty capsid shells of Qβ were reported . An overview of the development of vaccines from Qβ-derived VLPs ( virus-like particles ) can be found in Bachmann, Storni et al. (2020).
Individual evidence
- ↑ ICTV Master Species List 2018b v1 MSL # 34, Feb. 2019
- ↑ a b c d ICTV: ICTV Master Species List 2019.v1 , New MSL including all taxa updates since the 2018b release, March 2020 (MSL # 35)
- ↑ a b Kashiwagi A, Yomo T: Ongoing phenotypic and genomic changes in experimental coevolution of RNA bacteriophage Qβ and Escherichia coli . In: PLoS Genetics . 7, No. 8, August 2011, p. E1002188. doi : 10.1371 / journal.pgen.1002188 . PMID 21829387 . PMC 3150450 (free full text).
- ↑ J. van Duin, N. Tsareva: Single-stranded RNA phages. Chapter 15 . In: RL Calendar (Ed.): The Bacteriophages , Second. Edition, Oxford University Press, 2006, ISBN 0195148509 , pp. 175-196.
- ↑ Scientists Create Phage Capsid Nanoparticles That Prevent Viral Infection , on: SciTechDaily, March 31, 2020
- ↑ Influenza and Coronavirus Demise Could Lie with Phage Nanoparticles , on: genengnews.com (GEN) from March 31, 2020
- ↑ Daniel Lauster et al. : “Phage capsid nanoparticles with defined ligand arrangement block influenza virus entry”, in: Nature Nanotechnology of March 30, 2020, doi: 10.1038 / s41565-020-0660-2
- ↑ Martin F. Bachmann, Federico Storni et al : Vaccine against peanut allergy based on engineered virus-like particles displaying single major peanut allergens , in: Journal of Allergy and Clinical Immunology, Volume 145, No. 4, April 2020, p. 1240 -1253.e3, doi: org / 10.1016 / j.jaci.2019.12.007 , abstract , PDF