title: Staphylococcal pathogenicity island interference with helper phage reproduction is a paradigm of molecular parasitism.
abstract: Staphylococcal pathogenicity islands (SaPIs) carry superantigen and resistance genes and are extremely widespread in Staphylococcus aureus and in other Gram-positive bacteria. SaPIs represent a major source of intrageneric horizontal gene transfer and a stealth conduit for intergeneric gene transfer; they are phage satellites that exploit the life cycle of their temperate helper phages with elegant precision to enable their rapid replication and promiscuous spread. SaPIs also interfere with helper phage reproduction, blocking plaque formation, sharply reducing burst size and enhancing the survival of host cells following phage infection. Here, we show that SaPIs use several different strategies for phage interference, presumably the result of convergent evolution. One strategy, not described previously in the bacteriophage microcosm, involves a SaPI-encoded protein that directly and specifically interferes with phage DNA packaging by blocking the phage terminase small subunit. Another strategy involves interference with phage reproduction by diversion of the vast majority of virion proteins to the formation of SaPI-specific small infectious particles. Several SaPIs use both of these strategies, and at least one uses neither but possesses a third. Our studies illuminate a key feature of the evolutionary strategy of these mobile genetic elements, in addition to their carriage of important genes-interference with helper phage reproduction, which could ensure their transferability and long-term persistence.
authors.affiliation: Skirball Institute Program in Molecular Pathogenesis and Department of Microbiology, New York University Medical Center, New York, NY 10016, USA.
authors.forename: Geeta
authors.initials: G
authors.lastname: Ram
authors.forename: John
authors.initials: J
authors.lastname: Chen
authors.forename: Krishan
authors.initials: K
authors.lastname: Kumar
authors.forename: Hope F
authors.initials: HF
authors.lastname: Ross
authors.forename: Carles
authors.initials: C
authors.lastname: Ubeda
authors.forename: Priyadarshan K
authors.initials: PK
authors.lastname: Damle
authors.forename: Kristin D
authors.initials: KD
authors.lastname: Lane
authors.forename: José R
authors.initials: JR
authors.lastname: Penadés
authors.forename: Gail E
authors.initials: GE
authors.lastname: Christie
authors.forename: Richard P
authors.initials: RP
authors.lastname: Novick
mesh_terms: D000898:Antibiosis / Q000235:genetics*; D003001:Cloning, Molecular; D004926:Escherichia coli; D022761:Gene Transfer, Horizontal / Q000235:genetics*; D044404:Genomic Islands / Q000235:genetics*; D008854:Microscopy, Electron; D060888:Real-Time Polymerase Chain Reaction; D013204:Staphylococcus Phages / Q000502:physiology*; D013211:Staphylococcus aureus / Q000235:genetics* / Q000472:pathogenicity / Q000821:virology; D020798:Two-Hybrid System Techniques; D010948:Viral Plaque Assay; D014779:Virus Replication / Q000502:physiology*