Co-evolution within structured bacterial communities results in multiple expansion of CRISPR loci and enhanced immunity

eLife

Nora C Pyenson¹  Luciano A Marraffini² 

[1] Laboratory of Bacteriology, The Rockefeller University, New York, United States;Laboratory of Bacteriology, The Rockefeller University, New York, United States;Howard Hughes Medical Institute, The Rockefeller University, New York, United States;

关键词: CRISPR;    bacteriophage;    coevolution;    Other;   

DOI  :  10.7554/eLife.53078

来源: publisher

【 摘 要 】

Type II CRISPR-Cas systems provide immunity against phages and plasmids that infect bacteria through the insertion of a short sequence from the invader’s genome, known as the ‘spacer’, into the CRISPR locus. Spacers are transcribed into guide RNAs that direct the Cas9 nuclease to its target on the invader. In liquid cultures, most bacteria acquire a single spacer. Multiple spacer integration is a rare event which significance for immunity is poorly understood. Here, we found that when phage infections occur on solid media, a high proportion of the surviving colonies display complex morphologies that contain cells with multiple spacers. This is the result of the viral-host co-evolution, in which the immunity provided by the initial acquired spacer is easily overcome by escaper phages. Our results reveal the versatility of CRISPR-Cas immunity, which can respond with both single or multiple spacer acquisition schemes to solve challenges presented by different environments.

【 授权许可】

CC BY