Dear Editor,

Class 2 type V CRISPR-Cas12 effectors exhibit tremendous diversity, utilizing either single crRNAs or dual RNA guides to target double-stranded DNA (dsDNA), single-stranded DNA (ssDNA) or RNA. For dsDNA targets, Cas12 recognizes different PAM sequences and generates sticky ends on the target dsDNA.¹ This characteristic enhances the efficiency of homology-directed repair² and causes less off-target effects compared to SpCas9.³ Recent studies have identified a series of Cas12 nucleases, ranging from Cas12a to Cas12n,^1,4 thereby greatly expanding the gene editing toolkit. However, among the reported Cas12 proteins, the compact ones typically show limited gene editing efficiency and associate with long non-coding RNA guides or dual RNA (crRNA and tracrRNA) guides, which may compensate for the absence of certain Cas12 domains and enhance endonuclease activity and editing efficiency.⁵

 尊敬的编辑：

2 类 V 型 CRISPR-Cas12 效应子表现出巨大的多样性，利用单 crRNA 或双 RNA 向导靶向双链 DNA （dsDNA）、单链 DNA （ssDNA） 或 RNA。对于 dsDNA 靶标，Cas12 可识别不同的 PAM 序列并在靶标 dsDNA 上产生粘性末端。¹ 与 SpCas9 相比，此特性提高了同源定向修复的效率²，并导致更少的脱靶效应。³ 最近的研究确定了一系列 Cas12 核酸酶，范围从 Cas12a 到 Cas12n，1,4，从而大大扩展了基因编辑工具包。然而，在已报道的 Cas12 蛋白中，紧凑的蛋白通常表现出有限的基因编辑效率，并与长非编码 RNA 向导或双 RNA（crRNA 和 tracrRNA）向导相关，这可能会补偿某些 Cas12 结构域的缺失并增强核酸内切酶活性和编辑效率。⁵