title: Expression of phage P4 integrase is regulated negatively by both Int and Vis.
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.
authors.affiliation: Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Piazzolla
authors.affiliation: Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Calì
authors.affiliation: Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Spoldi
authors.affiliation: Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Forti
authors.affiliation: Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Sala
authors.affiliation: Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Magnoni
authors.affiliation: Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Dehò
authors.affiliation: Dipartimento di Scienze Biomolecolari e Biotecnologie, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Ghisotti
mesh_terms: D019677:Artificial Gene Fusion; D001287:Attachment Sites, Microbiological; D001483:Base Sequence; D003090:Coliphages / Q000201:enzymology / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics / Q000821:virology*; D015967:Gene Expression Regulation, Viral; D017930:Genes, Reporter; D019426:Integrases / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000032:analysis; D012367:RNA, Viral / Q000032:analysis; D014764:Viral Proteins / Q000502:physiology*; D001616:beta-Galactosidase / Q000032:analysis / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D012367:RNA, Viral; D014764:Viral Proteins; C098826:Vis protein, Bacteriophage P4; D019426:Integrases; D001616:beta-Galactosidase