Phage response to CRISPR-Encoded resistance in Streptococcus thermophilus
Phage response to CRISPR-Encoded resistance in Streptococcus thermophilus
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DOI：
10.1128/jb.01412-07
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发表时间：
2008-02-01
影响因子：
3.2
通讯作者：
Moineau, Sylvain
中科院分区：
文献类型：
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作者：
Deveau, Helene;Barrangou, Rodolphe;Moineau, Sylvain
规则间隔短回文重复序列（CRISPR）及其相关基因与对噬菌体的获得性抗性机制有关。细菌可以在CRISPR基因座内整合短的噬菌体衍生序列（间隔区），从而产生噬菌体抗性。在这项研究中，我们进一步表征了CRISPR 1作为嗜热链球菌中噬菌体抗性机制的效率。首先，我们证明了CRISPR 1与先前已知的噬菌体防御系统不同，并且对两种主要的S。嗜热菌对30株噬菌体不敏感突变株进行了分析。嗜热菌的研究表明，在CRISPR 1中添加一个新的间隔区是噬菌体攻击的最常见结果，并且重复添加间隔区增加了宿主的总体噬菌体抗性。添加的新间隔区具有29至31个核苷酸的大小，其中30个是迄今为止最常见的。对39个新获得的间隔区与野生型p2972、858和DT 1的完整基因组序列的比较分析表明，新添加的间隔区必须与噬菌体基因组中的一个区域（称为原间隔区）相同，以赋予噬菌体抗性表型。此外，我们发现了位于原间隔区下游的CRISPR 1特异性序列（NNAGAAW），该序列对于噬菌体抗性表型很重要。最后，我们通过对20个突变体的分析表明，毒力突变体通过单核苷酸突变和缺失迅速进化，以响应CRISPRI。
Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated genes are linked to a mechanism of acquired resistance against bacteriophages. Bacteria can integrate short stretches of phage-derived sequences (spacers) within CRISPR loci to become phage resistant. In this study, we further characterized the efficiency of CRISPR1 as a phage resistance mechanism in Streptococcus thermophilus. First, we show that CRISPR1 is distinct from previously known phage defense systems and is effective against the two main groups of S. thermophilus phages. Analyses of 30 bacteriophage-insensitive mutants of S. thermophilus indicate that the addition of one new spacer in CRISPR1 is the most frequent outcome of a phage challenge and that the iterative addition of spacers increases the overall phage resistance of the host. The added new spacers have a size of between 29 to 31 nucleotides, with 30 being by far the most frequent. Comparative analysis of 39 newly acquired spacers with the complete genomic sequences of the wild-type phages 2972, 858, and DT1 demonstrated that the newly added spacer must be identical to a region (named proto-spacer) in the phage genome to confer a phage resistance phenotype. Moreover, we found a CRISPR1-specific sequence (NNAGAAW) located downstream of the proto-spacer region that is important for the phage resistance phenotype. Finally, we show through the analyses of 20 mutant phages that virulent phages are rapidly evolving through single nucleotide mutations as well as deletions, in response to CRISPRI.