Interactions between the regulatory repressors of phage P2 and host proteins, a puzzling story
(English)Manuscript (preprint) (Other academic)
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.
bacteriophages, P2, E. coli, transcriptional switch, protein-protein interactions, KEIO, yeast-two-hybrid
IdentifiersURN: urn:nbn:se:su:diva-74030OAI: oai:DiVA.org:su-74030DiVA: diva2:506164