Restricting Promiscuity

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Science  09 Jul 2010:
Vol. 329, Issue 5988, pp. 121
DOI: 10.1126/science.329.5988.121-b

Although it might seem that many species of bacteria swap DNA promiscuously, in reality, the transfer of genetic information is curtailed by sequence-specific restriction systems. Several such systems have been characterized; the core component is an endonuclease that cleaves unmodified DNA (the host's own DNA is protected against digestion, usually by methylation). Corvaglia et al. have discovered a new endonuclease in Staphylococcus aureus, which is a potentially pathogenic bacterium carried by up to half the human population. Methicillin-resistant strains of S. aureus (MRSA) were found to carry mutations in this restriction endonuclease, which has tentatively been assigned to the type III family; these mutations probably render these strains hypersusceptible to the uptake of antibiotic-resistance genes from gut bacteria.

Proc. Natl. Acad. Sci. U.S.A. 107, 10.1073/pnas.1000489107 (2010).

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