Salmonella virus P22

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Salmonella virus P22
Systematics
Classification : Viruses
Area : Duplodnaviria
Empire : Heunggongvirae
Phylum : Uroviricota
Class : Caudoviricetes
Order : Caudovirales
Family : Podoviridae
Genre : Leather Mountain Virus
Type : Salmonella virus P22
Taxonomic characteristics
Genome : dsDNA linear
Baltimore : Group 1
Symmetry : icosahedral
Cover : no
Scientific name
Salmonella virus P22
Short name
P22
Left
NCBI  Taxonomy: 10754
ViralZone ( ExPASy , SIB): 519 (gender)

Salmonella virus P22 ( scientifically Salmonella virus P22 , obsolete: Enterobacteria phage P22 , Phage P22 ) is a bacteriophage (bacterial virus ) from the genus Lederbergvirus (formerly P22virus , P22likevirus , P22-like viruses , P22-like phages ) in the family Podoviridae . Its hosts are salmonella of the serotype Typhimurium (scientifically Salmonella enterica subsp. Enterica ser. Typhimurium). Like many other bacteriophages, it is used in molecular biologyto induce mutations in cultured bacteria and introduce foreign genetic material . P22 has been used in generalized transduction and is an important tool in studying the genetics of Salmonella.

Structure and system

P22 is very similar in genetics and mode of action to bacteriophage λ ( Escherichia virus lambda ). The genome of P22, as with lambda of double-stranded DNA However, the genes for the construction of different virion (virus particle) encoding from those of the lambda phage.

The head of the P22 virions has an icosahedral symmetry with a triangulation number T = 7, its diameter is 60  nm . There is a short tail on it, which identifies it as a member of the Podoviridae family .

The tail protein ( English tailspike protein ) of P22 is anchored in the viral envelope and serves to permit penetration into the membrane of the host cells. The tailspike of P22 (called gp9) has an unusual beta-helix fold.

The bacteriophage E34 (alias Salmonella phage 34 or Bacteriophage ε 34 ) is now considered a variant of P22 within the species Salmonella virus P22 .

Traditionally P22 was with viruses of similar short-tailed morphology , genome transcription brought and reproduction cycles in connection, in particular the lambda phage and other lambdoid phage (phage of the genus Lambda Virus , formerly English lambda-like phages , lambda-like viruses , lambda Like Virus called ). Today, however, this relationship is considered overrated and the genus Lambdavirus is now placed in a different phage family Siphoviridae within the order Caudovirales of the tailed viruses.

The bacillus phage Phi29 (Φ29, officially Bacillus virus phi29 ) also has a morphology similar to the lambda phage, but also has little in common with P22 in the genome. Φ29 is therefore now also (as a species) placed in another independent family Podoviridae within the order Caudovirales .

The NCBI currently carries the following viruses in the species Salmonella virus P22 :

  • Salmonella phage 22
  • Salmonella phage 25
  • Salmonella phage 34
  • Salmonella phage P22-pbi

Genome

The virus particles (virions) of P22 have a single double-stranded DNA molecule ( dsDNA ), i. H. an unsegmented genome (monopartite). Its length is about 44  kbp (kilobase pairs). The genome of P22 was sequenced in 2006 and 65 genes were identified. The genome length of the “wild type” of P22 is only about 42 kbp. The results of the sequencing support the hypothesis that P22 has a mosaic-like genome and was created through extensive recombination with the other virus.

Research on P22 has long focused on the differences to bacteriophage λ, particularly with regard to the mechanisms by which the DNA is passed on in the event of an infection and how it is packaged in the virions.

A so-called concatamer is initially formed from the DNA molecules generated by rolling-circle DNA replication . This involves a doubling of about 4% of the DNA sequence at both ends. I.e. At the end of the DNA strand there is still a short piece from the beginning, and vice versa. The capsid of the phage head has more space than is required for exactly 100% of the DNA sequence. This is known as headful packaging , as the replicated DNA is 'stuffed' into the phage head of the virion until it is full, rather than filling each virion with an exact 1: 1 copy of the DNA sequence. In total, the virion then normally contains 48 kbp.

Since the DNA packaged in the capsid is linear, it must be circularized for rolling circle DNA replication after infection of the host bacterium. H. be closed in a ring. This takes place through a homologous recombination between the direct repetitions at the two overlapping ends of the still linear DNA strand. The recombination enzymes required for this are either results of the translation of the host's own rec gene coding for them . In the event that these are not available, however, P22 also brings its own such recombination function genes with it. The resulting circular DNA, with the copy of the P22 nucleotide sequence, is the substrate (starting material) for gene expression and DNA replication.

Propagation cycle

infection

The infection begins when the tail of the P22 phage binds to the O antigen - lipopolysaccharide on the surface of the salmonella of the serotype Typhimurium. The virion's tail fiber protein functions as an endorhamnosidase that cleaves the O-antigen chain. After infection, P22 can enter either a lytic or a lysogenic growth pathway.

  • Virus replication begins on the lytic pathway immediately after infection and releases around 300–500 phage progeny within one hour via cell lysis .
  • On the lysogenic pathway , however, the phage DNA integrates into the host genome and is passed on to daughter cells through cell division ( temperate phage).

The main factor that controls the growth path is the multitude of infections ( English multiplicity of infection , moi); a high moi value favors the lysogenic pathway, a lower one the lytic pathway.

Assembly

In the course of assembly (the assembly of the virus particles), P22, like other large dsDNA viruses, first builds a “procapsid” structure and then packs the DNA genome into it. The P22-Procapsid is made of a well-studied protein (coat protein, English coat protein assembled): During assembly about 250 molecules of a scaffold protein (are English scaffolding protein ) present in Procapsid. This is released again as the DNA packaging progresses. The released scaffold protein is not damaged and can reassemble with newly synthesized coat protein to form more procapsids. Its function is therefore actually that of a scaffolding . Since it mediates the assembly of other proteins without becoming part of the finished structure, it is by definition catalytic . In laboratory infections, scaffold protein molecules participate in an average of 5 rounds of procapsid assembly.

The involvement of a scaffold protein in the assembly of the procapsid is also common with other large viruses with an icosahedral shape, for example with the herpes viruses that infect eukaryotes . However, in some cases, the scaffold is proteolytically removed instead of being reused.

In addition, the P22 scaffold protein suppresses its own synthesis as long as no procapsids are assembled with its help. This is one of the few known examples where the synthesis of a virion structural protein is modulated (influenced) by the assembly process.

The proteins generated by three genes are required to stabilize the DNA condensed in the P22 phage capsids: Gp4, Gp10 and Gp26. These proteins clog the opening through which the DNA enters. These three proteins appear to polymerize on the newly filled capsids and thus form the neck of the mature phage, through which the DNA is later injected into the host cell during infection. Gp4 ( English tail accessory factor , tail accessory factor ' of P22) is attached to the first straight-filled with DNA capsids. In solution, the protein acts as a monomer and has poor structural stability. When assembling the tail, two non-identical sets of six gp4 monomers are attached. Gp4 acts as a structural adapter for gp10 and gp26, the other two components ('accessory factors') of the tail.

Application in salmonella genetics

The transduction (gene transfer between bacteria by virus) is used extensively in the bacteria, and, in the genetic engineering production of new strains ( English strains ) are useful. In general, transduction within each bacterial species (species) requires the use of a specific phage, since most phages have a very narrow host range. For example, P22 is used for transduction into the serotype Salmonella enterica sv. Typhimurium used. P22 is particularly stable in storage, stocks with high titers are easy to obtain and there were mutants with Hochfrequenztransduktion ( English high-frequency transduction , HT) is isolated.

Individual evidence

  1. ↑ a b c d ICTV: ICTV Taxonomy history: Enterobacteria phage T4 , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
  2. ↑ a b c d e f g h i j Peter E. Prevelige Jr .; Richard Lane Calendar (Ed.): The Bacteriophages , 2nd Edition, Oxford University Press, New York, New York 2006, ISBN 978-0-19-514850-3 , pp. 457-468.
  3. ↑ Snyder L, Champness W: Molecular Genetics of Bacteria , 3rd. Edition, ASM Press, 2007, ISBN 978-1-55581-399-4 .
  4. ↑ a b c d e f g h i j k l m n o p q r s Sherwood Casjens: Information about bacteriophage P22 . In: ASM Division M: Bacteriophage P22 . American Society for Microbiology. Archived from the original on December 26, 2010. Retrieved April 15, 2012.
  5. ↑ a b NCBI: Salmonella phage 34 (no rank)
  6. ↑ Robert Villafane, Milka Zayas, Eddie B. Gilcrease, Andrew M. Kropinski, Sherwood R. Casjens: Genomic analysis of bacteriophage ε 3 4 of Salmonella enterica serovar Anatum (15+) , in: BMC Microbiol. 8, p. 227, December 17, 2008, doi: 10.1186 / 1471-2180-8-227 , PMC 2629481 (free full text), PMID 19091116
  7. ^ H. W. Ackermann: The lambda - P22 problem . In: Bacteriophage . 5, No. 1, May 21, 2012, p. E1017084. doi : 10.1080 / 21597081.2015.1017084 . PMID 26442187 . PMC 4422791 (free full text).
  8. ↑ NCBI: Bacillus virus phi29 (species)
  9. ↑ NCBI: Salmonella virus P22 (species)
  10. ↑ S. Casjens, M. Hayden: Analysis in vivo of the bacteriophage P22 headful nuclease . In: J. Mol. Biol. 189, Feb. 5, 1988, pp. 467-474. doi: 10.1016 / 0022-2836 (88) 90618-3 , PMID 3280806
  11. ↑ G. Streisinger, R. Edgar, M. Stahl: Chromosome structure in phage T4. I. Circularity of the linkage map . In: Proc. Natl. Acad. Sci. USA 57, May 1964, pp. 775-779. doi: 10.1073 / pnas.51.5.775 , PMC 300161 (free full text)
  12. ↑ S. Casjens, E. Wyckoff, M. Hayden, L. Sampson, K. Eppler, S. Randall, E. Moreno, P. Serwer: The bacteriophage P22 portal protein is part of the gauge that determines the length and packing density of intravirion DNA . In: J. Mol. Biol. 224, 1992, pp. 1055-1074. doi: 10.1016 / 0022-2836 (92) 90469-Z , PMID 1569567
  13. ↑ M. Susskind, D. and Botstein: Molecular genetics of bacteriophage P22 . In: Microbiol. Rev. 42, June 1978, pp. 385-413. PMC 281435 (free full text), PMID 353481
  14. ^ H. Strauss, J. King: Steps in the stabilization of newly packaged DNA during phage P22 morphogenesis . In: J. Mol. Biol. . 172, No. 4, February 1984, pp. 523-543. doi : 10.1016 / S0022-2836 (84) 80021-2 . PMID 6363718 .
  15. ↑ Eppler K, Wyckoff E, Goates J, Parr R, Casjens S: Nucleotide sequence of the bacteriophage P22 genes required for DNA packaging . In: Virology . 183, No. 2, August 1991, pp. 519-538. doi : 10.1016 / 0042-6822 (91) 90981-G . PMID 1853558 .
  16. ↑ Olia AS, Al-Bassam J, Winn-Stapley DA, Joss L, Casjens SR, Cingolani G: Binding-induced stabilization and assembly of the phage P22 tail accessory factor gp4. . In: J Mol Biol . 363, No. 2, October 20, 2006, pp. 558-576. doi : 10.1016 / j.jmb.2006.08.014 . PMID 16970964 .
  17. ↑ a b c B. L. Neal, PK Brown, PR Reeves: Use of Salmonella Phage P22 for Transduction in Escherichia coli . In: Journal of Bacteriology . 175, No. 21, November 1993, pp. 7115-7118. doi : 10.1128 / jb.175.21.7115-7118.1993 . PMID 8226656 . PMC 206843 (free full text).

Web links

  • Stanley Maloy: Genetic Background - Phage P22 , at: San Diego State University (SDSU) - via web archive
  • Schaefer KL, McClure WR: Antisense RNA control of gene expression in bacteriophage P22. I. Structures of sar RNA and its target, ant mRNA . In: RNA . 3, No. 2, February 1997, pp. 141-156. PMID 9042942 . PMC 1369469 (free full text). ( Sar-RNA )