The Type 2 dUTPase of Bacteriophage φNM1 Initiates Mobilization of Staphylococcus aureus Bovine Pathogenicity Island 1

Staphylococcus aureus pathogenicity islands (SaPIs) are genetic elements that are mobilized by specific helper phages. The initial step in mobilization is the derepression of the SaPI by the interaction of a phage protein with the SaPI master repressor StI. Stl proteins are highly divergent between different SaPIs and respond to different phage-encoded derepressors. One such SaPI, SaPlbov1, is derepressed by the dUTPase (Dut) of bacteriophage 80 alpha (Dut(80 alpha)) and its phage phi(11) homolog, Dut(11). We previously showed that SaPlbov1 could also be mobilized by phage phi NM1, even though its dut gene is not homologous with that of 80a. Here, we show that phi NM1 dutencodes a type 2 dUTPase (Dut(NM1)), which has an a-helical structure that is distinct from the type 1 trimeric, beta-sheet structure of Dut(80 alpha). Deletion of dut(NM1) abolishes the ability of phi NM1 to mobilize SaPlbov1. Like Dut(80 alpha), Dut(NM1) forms a direct interaction with SaPlbov1 Stl both in vivo and in vitro, leading to inhibition of the dUTPase activity and StI release from its target DNA. This work provides novel insights into the diverse mechanisms of genetic mobilization in S. aureus. (C) 2015 Elsevier Ltd. All rights reserved.