Structure-guided engineering allows researchers access to an expanding number of Cas9 variants that relax the constraint imposed by target site recognition of a protospacer-adjacent motif (PAM).

中文翻译：

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少PAM就是更多。

结构导向的工程技术使研究人员可以访问数量不断增加的Cas9变体，从而放松了由靶位识别邻近原间隔物（PAM）所产生的限制。