ISP, Université de Tours, INRAE, Tours, France; Dangé-Saint-Romain, France.
Service de Bactériologie-Virologie-Hygiène Hospitalière, CHRU de Tours, Tours, France; Dangé-Saint-Romain, France.
CRISPR J. 2021 Apr;4(2):233-242. doi: 10.1089/crispr.2020.0145.
Nearly all strains of , the leading cause of invasive infections in neonates, encode a type II-A clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system. Interestingly, strains belonging to the hypervirulent Sequence Type 17 (ST17) contain significantly fewer spacers in their CRISPR locus than other lineages, which could be the result of a less functional CRISPR-Cas system. Here, we revealed one large deletion in the ST17 promoter region and we evaluated its impact on the transcription of genes as well as the functionalities of the CRISPR-Cas system. We demonstrated that Cas9 interference is functional and that the CRISPR-Cas system of ST17 strains can still acquire new spacers, despite the absence of a regular promoter. We demonstrated that a promoter sequence upstream of a small RNA partially overlapping the antisense tracrRNA, is responsible for the ST17 CRISPR-Cas adaptation and interference activities.
几乎所有导致新生儿侵袭性感染的主要病原体都编码一种 II-A 型簇状规则间隔短回文重复序列 (CRISPR)-Cas 系统。有趣的是，属于强毒力序列类型 17（ST17）的菌株在其 CRISPR 基因座中的间隔区数量明显少于其他谱系，这可能是 CRISPR-Cas 系统功能较弱的结果。在这里，我们揭示了 ST17 启动子区域的一个大型缺失，并评估了其对基因转录以及 CRISPR-Cas 系统功能的影响。我们证明 Cas9 干扰是有效的，并且尽管没有常规的启动子，ST17 菌株的 CRISPR-Cas 系统仍然可以获得新的间隔区。我们证明了位于小 RNA 上游的启动子序列部分与反义 tracrRNA 重叠，负责 ST17 CRISPR-Cas 的适应和干扰活性。
