Abstract：
Pyrococcus furiosus is a hyperthermophilic archaeon with three effector CRISPR complexes (types I-A, I-B, and III-B) that each employ crRNAs derived from seven CRISPR arrays. Here, we investigate the CRISPR adaptation response to a newly discovered and self-transmissible plasmid, pT33.3. Transconjugant strains of Pyrococcus furiosus exhibited dramatically elevated levels of new spacer integration at CRISPR loci relative to the strain harboring a commonly employed, laboratory-constructed plasmid. High-throughput sequence analysis demonstrated that the vast majority of the newly acquired spacers were preferentially selected from DNA surrounding a particular region of the pT33.3 plasmid and exhibited a bi-directional pattern of strand bias that is a hallmark of primed adaptation by type I systems. We observed that one of the CRISPR arrays of our Pyrococcus furiosus laboratory strain encodes a spacer that closely matches the region of the conjugative plasmid that is targeted for adaptation. The hyper-adaptation phenotype was found to strictly depend both on the presence of this single matching spacer as well as the I-B effector complex, known to mediate primed adaptation. Our results indicate that Pyrococcus furiosus naturally encountered this conjugative plasmid or a related mobile genetic element in the past and responds to reinfection with robust primed adaptation.
摘要：
焦球菌是一种嗜高温古细菌，具有三个效应CRISPR复合物（I-A型，I-B,和III-B），每个都使用源自七个CRISPR阵列的crRNA。这里,我们研究了CRISPR对新发现的自我传播质粒的适应反应，pT33.3.与通常使用的菌株相比，在CRISPR基因座处的新间隔子整合水平显着升高，实验室构建的质粒。高通量序列分析表明，绝大多数新获得的间隔区优先选择自pT33.3质粒特定区域周围的DNA，并表现出双向的链偏倚模式，这是I型系统引发适应的标志。我们观察到，我们的热球菌实验室菌株的CRISPR阵列之一编码一个间隔区，该间隔区与靶向适应的接合质粒区域紧密匹配。发现超适应表型严格取决于该单个匹配间隔区以及I-B效应子复合物的存在。已知调解启动适应。我们的结果表明，过去的热球菌自然遇到了这种接合质粒或相关的可移动遗传元件，并以强大的启动适应性对再感染做出反应。
