The site-specific integration system of the temperate Streptococcus thermophilus bacteriophage phiSfi21.
The temperate bacteriophage phiSfi21 integrates its DNA into the chromosome of Streptococcus thermophilus strains via site-specific recombination. Nucleotide sequencing of the attachment sites identified a 40-bp identity region which surprisingly overlaps both the 18-terminal bp of the phage integrase gene and the 11-terminal bp of a host tRNAArg gene. A 2.4-kb phage DNA segment, covering attP, the phage integrase, and a likely immunity gene contained all the genetic information for faithful integration of a nonreplicative plasmid into the attB site. A deletion within the int gene led to the loss of integration proficiency. A number of spontaneous deletions were observed in plasmids containing the 2.4-kb phage DNA segment. The deletion sites were localized to the tRNA side of the identity region and to phage or vector DNA with 3- to 6-bp-long repeats from the border region. A similar type of deletion was previously observed in a spontaneous phage mutant.
Bruttin
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A
Nestlé Research Centre, Nestec Ltd., Vers-chez-les-Blanc, Lausanne 26, CH-1000, Switzerland.
Foley
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S
Brüssow
H
H
D001435:Bacteriophages / Q000502:physiology*; D001483:Base Sequence; D017353:Gene Deletion; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D010957:Plasmids; D011995:Recombination, Genetic; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013291:Streptococcus / Q000821:virology*; D016662:Virus Integration