PMID:16847139

Citation	Piazzolla, D, Calì, S, Spoldi, E, Forti, F, Sala, C, Magnoni, F, Dehò, G and Ghisotti, D (2006) Expression of phage P4 integrase is regulated negatively by both Int and Vis. J. Gen. Virol. 87:2423-31
Abstract	Phage P4 int gene encodes the integrase responsible for phage integration into and excision from the Escherichia coli chromosome. Here, the data showing that P4 int expression is regulated in a complex manner at different levels are presented. First of all, the Pint promoter is regulated negatively by both Int and Vis, the P4 excisionase. The N-terminal portion of Int appears to be sufficient for such a negative autoregulation, suggesting that the Int N terminus is implicated in DNA binding. Second, full-length transcripts covering the entire int gene could be detected only upon P4 infection, whereas in P4 lysogens only short 5'-end covering transcripts were detectable. On the other hand, transcripts covering the 5'-end of int were also very abundant upon infection. It thus appears that premature transcription termination and/or mRNA degradation play a role in Int-negative regulation both on the basal prophage transcription and upon infection. Finally, comparison between Pint-lacZ transcriptional and translational fusions suggests that Vis regulates Int expression post-transcriptionally. The findings that Vis is also an RNA-binding protein and that Int may be translated from two different start codons have implications on possible regulation models of Int expression.
Links	PubMed Online version:10.1099/vir.0.81875-0
Keywords	Artificial Gene Fusion; Attachment Sites, Microbiological; Base Sequence; Coliphages/enzymology; Coliphages/genetics; DNA-Binding Proteins/biosynthesis; DNA-Binding Proteins/genetics; DNA-Binding Proteins/physiology; Escherichia coli/genetics; Escherichia coli/virology; Gene Expression Regulation, Viral; Genes, Reporter; Integrases/biosynthesis; Integrases/genetics; Molecular Sequence Data; Protein Binding; Protein Structure, Tertiary; RNA, Messenger/analysis; RNA, Viral/analysis; Viral Proteins/physiology; beta-Galactosidase/analysis; beta-Galactosidase/genetics
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BPP4:VINT		GO:0039695: DNA-templated viral transcription	ECO:0000315:		P		Figure 3 shows increasingly inhibited Int promoter transcription as increasingly larger fractions of the P4 Int gene are expressed. "Thus, when the P4 DNA fragment contained the whole int gene (pGM606) or at least 60 % of it (pGM605), the int mRNA abundance was greatly reduced, suggesting that Int negatively regulates transcription initiation at P int."	complete CACAO 11996

References

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