| Autor: |
Malone LM; Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand., Warring SL; Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand., Jackson SA; Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.; Genetics Otago, University of Otago, Dunedin, New Zealand., Warnecke C; Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.; Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland., Gardner PP; Genetics Otago, University of Otago, Dunedin, New Zealand.; Department of Biochemistry, University of Otago, Dunedin, New Zealand., Gumy LF; Department of Anatomy, University of Otago, Dunedin, New Zealand., Fineran PC; Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand. peter.fineran@otago.ac.nz.; Genetics Otago, University of Otago, Dunedin, New Zealand. peter.fineran@otago.ac.nz. |
| Abstrakt: |
CRISPR-Cas systems provide bacteria with adaptive immunity against bacteriophages 1 . However, DNA modification 2,3 , the production of anti-CRISPR proteins 4,5 and potentially other strategies enable phages to evade CRISPR-Cas. Here, we discovered a Serratia jumbo phage that evades type I CRISPR-Cas systems, but is sensitive to type III immunity. Jumbo phage infection resulted in a nucleus-like structure enclosed by a proteinaceous phage shell-a phenomenon only reported recently for distantly related Pseudomonas phages 6,7 . All three native CRISPR-Cas complexes in Serratia-type I-E, I-F and III-A-were spatially excluded from the phage nucleus and phage DNA was not targeted. However, the type III-A system still arrested jumbo phage infection by targeting phage RNA in the cytoplasm in a process requiring Cas7, Cas10 and an accessory nuclease. Type III, but not type I, systems frequently targeted nucleus-forming jumbo phages that were identified in global viral sequence datasets. The ability to recognize jumbo phage RNA and elicit immunity probably contributes to the presence of both RNA- and DNA-targeting CRISPR-Cas systems in many bacteria 1,8 . Together, our results support the model that jumbo phage nucleus-like compartments serve as a barrier to DNA-targeting, but not RNA-targeting, defences, and that this phenomenon is widespread among jumbo phages. |
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