Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Interactions between the regulatory repressors of phage P2 and host proteins, a puzzling story
Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
J. Craig venter institute.
Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
Show others and affiliations
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Bacteriophage P2 belongs to a group of P2-like phages that have been classified as non-inducible. This is based on the fact that they are not induced by UV light, and upon inactivation of the repressor the bacteria will die but no progeny phage is produced. When the prophage is derepressed it is replicated in situ, but unable to excise due to a lack of integrase. The transcriptional switch of phage P2 contains two repressors, the immunity repressor C and the Cox repressor. The C gene is transcribed from the Pc promoter that also controls the integrase gene, and the C repressor controls the early Pe promoter. The cox gen is transcribed from the Pe promoter and the Cox repressor controls the Pc promoter, making the two promoters mutually exclusive. Thus, the integrase cannot be expressed at the same time as Cox and both proteins are required for phage excision. To try to resolve this paradox, a two-hybrid screen has been performed to find possible host proteins that interact with C or Cox that could control the transcriptional switch.

Eight E. coli proteins showed interactions with C and three with Cox, out of which all also interacted with C. One of the candidate genes is known to be a "sticky" protein, and was not analysed further. Using a plasmid containing the transcriptional switch, we found that deletions of two of the candidate genes encoding proteins interacting with C or Cox gave a reduced percentage of plasmids choosing the lysogenic pathway; the E. coli yeeD and yqjG genes. YeeD interacts with C as well as Cox, and it is a conserved 8 kD hypothetical proteins with a SirA motif, and YqjG is a predicted glutathione S-transferase. More studies are required to clarify their involvement of these genes in regulating the transcriptional switch.

Keyword [en]
bacteriophages, P2, E. coli, transcriptional switch, protein-protein interactions, KEIO, yeast-two-hybrid
National Category
Genetics
Identifiers
URN: urn:nbn:se:su:diva-74030OAI: oai:DiVA.org:su-74030DiVA: diva2:506164
Available from: 2012-02-28 Created: 2012-02-27 Last updated: 2012-02-28Bibliographically approved
In thesis
1. A Genetic Switch in Bacteriophages within the Peduovirinae Subfamily: Structure, Function and Evolution
Open this publication in new window or tab >>A Genetic Switch in Bacteriophages within the Peduovirinae Subfamily: Structure, Function and Evolution
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The temperate bacteriophages in the Peduovirinae subfamily can either grow lytically or integrate into their bacterial host and form lysogeny. Which one of the two life cycles the phage will enter after infection is controlled by a transcriptional switch. The switch also controls the induction of genes necessary for an integrated phage, a prophage, to excise out of the host genome and propagate lytically. In its most simple form, the transcriptional switch consists of two proteins repressing each other’s promoters, which are oriented face to face in close proximity.

The Peduovirinae phages contain two types of transcriptional switches. They were studied with phylogenetic methods to determine their evolution and distribution. Bioinformatic analyses showed that there were several new E. coli integration sites and new inferred immunity classes among the Peduovirinae phages. The two switch types fell into two distinct groups, with no overlap in any of the proteins, but these groups were not defined by host barriers. But in vivo distribution did show a host preference.

The P2 C protein was crystallized and its 3D structure determined. It forms a symmetrical dimer in vitro, with an unstructured C-terminal end. The DNA binding domain was determined to lie in alpha helix three and narrowed down to three residues. The C terminal end of the protein is suggested to be part of tetramerization, but a nine amino acid truncation does not affect activity in vitro.

In an attempt to discover the mechanism between the switch from lysogeny to lysis in phage P2 the interactions between the two switch proteins and the proteins of its host E. coli was analyzed. Eight E. coli proteins interacted with protein C or Cox, but no interaction between the two switch proteins was detected. Two E. coli proteins showed a distinct effect on the expression of C, and several affected the level of phage lysis. The mechanisms behind these effects are still unclear.

Place, publisher, year, edition, pages
Stockholm: Department of Genetics, Microbiology and Toxicology, Stockholm University, 2012. 88 p.
National Category
Genetics
Research subject
Molecular Genetics
Identifiers
urn:nbn:se:su:diva-74031 (URN)978-91-7447-467-1 (ISBN)
Public defence
2012-03-30, Magnelisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (English)
Opponent
Supervisors
Note
At the time of the doctoral defence the following paper was unpublished and had a status as follows: Paper nr 3: ManuscriptAvailable from: 2012-03-08 Created: 2012-02-27 Last updated: 2012-03-01Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Nilsson, HannaOdegrip, RichardNilsson, AndersHaggård-Ljungquist, Elisabeth
By organisation
Department of Genetics, Microbiology and Toxicology
Genetics

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 85 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf