Genetic analysis of the DNA recognition sequence of the P2 Cox protein

Vries, Garry Cores de; Wu, Xiushan; Haggård‐Ljungquist, Elisabeth

doi:10.1128/jvi.65.9.4665-4669.1991

“…Three more genes have been identified in this region: the ogr gene controlling P2 late-gene expression (231), the old gene (212), and the ccx gene (94). The Cox protein is involved in (i) excision of the integrated P2 prophage genome (150, 243a); (ii) transcriptional repression of the P2pc promoter, which controls the synthesis of the immunity repressor C and the integrase (50,201); and (iii) transcriptional activation of the PLL promoter of P4 (202). The P2 nonessential old gene product kills E. coli recB and recC mutants and interferes with the growth of phage lambda (212,213); this latter property is used for the selection of…”

Section: Genome Organization Of P2 and P4mentioning

confidence: 99%

Mechanisms of genome propagation and helper exploitation by satellite phage P4.

Lindqvist

¹

,

Dehò

²

,

Calendar

³

1993

Microbiological Reviews

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“…Three more genes have been identified in this region: the ogr gene controlling P2 late-gene expression (231), the old gene (212), and the ccx gene (94). The Cox protein is involved in (i) excision of the integrated P2 prophage genome (150, 243a); (ii) transcriptional repression of the P2pc promoter, which controls the synthesis of the immunity repressor C and the integrase (50,201); and (iii) transcriptional activation of the PLL promoter of P4 (202). The P2 nonessential old gene product kills E. coli recB and recC mutants and interferes with the growth of phage lambda (212,213); this latter property is used for the selection of old """old VOL.…”

Section: Genome Organization Of P2 and P4mentioning

confidence: 99%

Mechanisms of genome propagation and helper exploitation by satellite phage P4

Lindqvist

¹

,

Dehò

²

,

Calendar

³

1993

View full text Add to dashboard Cite

Temperate coliphage P2 and satellite phage P4 have icosahedral capsids and contractile tails with side tail fibers. Because P4 requires all the capsid, tail, and lysis genes (late genes) of P2, the genomes of these phages are in constant communication during P4 development. The P4 genome (11,624 bp) and the P2 genome (33.8 kb) share homologous cos sites of 55 bp which are essential for generating 19-bp cohesive ends but are otherwise dissimilar. P4 turns on the expression of helper phage late genes by two mechanisms: derepression of P2 prophage and transactivation of P2 late-gene promoters. P4 also exploits the morphopoietic pathway of P2 by controlling the capsid size to fit its smaller genome. The P4 sid gene product is responsible for capsid size determination, and the P2 capsid gene product, gpN, is used to build both sizes. The P2 capsid contains 420 capsid protein subunits, and P4 contains 240 subunits. The size reduction appears to involve a major change of the whole hexamer complex. The P4 particles are less stable to heat inactivation, unless their capsids are coated with a P4-encoded decoration protein (the psu gene product). P4 uses a small RNA molecule as its immunity factor. Expression of P4 replication functions is prevented by premature transcription termination effected by this small RNA molecule, which contains a sequence that is complementary to a sequence in the transcript that it terminates.

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