Moonlighting bacteriophage proteins derepress staphylococcal pathogenicity islands.
Staphylococcal superantigen-carrying pathogenicity islands (SaPIs) are discrete, chromosomally integrated units of approximately 15 kilobases that are induced by helper phages to excise and replicate. SaPI DNA is then efficiently encapsidated in phage-like infectious particles, leading to extremely high frequencies of intra- as well as intergeneric transfer. In the absence of helper phage lytic growth, the island is maintained in a quiescent prophage-like state by a global repressor, Stl, which controls expression of most of the SaPI genes. Here we show that SaPI derepression is effected by a specific, non-essential phage protein that binds to Stl, disrupting the Stl-DNA complex and thereby initiating the excision-replication-packaging cycle of the island. Because SaPIs require phage proteins to be packaged, this strategy assures that SaPIs will be transferred once induced. Several different SaPIs are induced by helper phage 80alpha and, in each case, the SaPI commandeers a different non-essential phage protein for its derepression. The highly specific interactions between different SaPI repressors and helper-phage-encoded antirepressors represent a remarkable evolutionary adaptation involved in pathogenicity island mobilization.
Tormo-Más
María Angeles
MA
Centro de Investigación y Tecnología Animal, Instituto Valenciano de Investigaciones Agrarias (CITA-IVIA), Apdo. 187, Segorbe, Castellón 12400, Spain.
Mir
Ignacio
I
Shrestha
Archana
A
Tallent
Sandra M
SM
Campoy
Susana
S
Lasa
Iñigo
I
Barbé
Jordi
J
Novick
Richard P
RP
Christie
Gail E
GE
Penadés
José R
JR
D000483:Alleles; D000595:Amino Acid Sequence; D004247:DNA / Q000096:biosynthesis / Q000235:genetics; D004261:DNA Replication; D044404:Genomic Islands / Q000235:genetics*; D006378:Helper Viruses / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D008242:Lysogeny / Q000502:physiology; D008969:Molecular Sequence Data; D039002:Prophages / Q000378:metabolism / Q000502:physiology; D011755:Pyrophosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic / Q000235:genetics; D012097:Repressor Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D012772:Shock, Septic; D013204:Staphylococcus Phages / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D013211:Staphylococcus aureus / Q000235:genetics* / Q000472:pathogenicity / Q000821:virology; D018089:Superantigens / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics*; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D012097:Repressor Proteins; D018089:Superantigens; D014764:Viral Proteins; D004247:DNA; D011755:Pyrophosphatases; C020020:dUTP pyrophosphatase
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