Methods for making specific modifications to the genomes of living cells are powerful research tools. Two methods currently dominate, CRISPR and Cre recombinase. CRISPR has the advantage that it can act on unmodified target genes; Cre has the advantage of being available in drug-inducible versions, allowing temporal control, but it requires engineering (“floxing”) of the target gene. Here, we have combined these advantages by constructing drug (tamoxifen/mifepristone)-inducible Cas9 and Cpf1 CRISPR effectors. We demonstrate their low background activity and robust activation with drugs, by using gRNAs to target them to TetR, in a cell carrying a Tet-repressed reporter gene. As well as being useful in their own right, the research tools generated here will pave the way to making further drug-inducible effector proteins.

中文翻译：

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他莫昔芬和米非司酮诱导型 CRISPR 效应器、Cas9 和 Cpf1

对活细胞基因组进行特定修饰的方法是强大的研究工具。目前有两种方法占主导地位，CRISPR 和 Cre 重组酶。CRISPR的优势在于可以作用于未修饰的靶基因；Cre 具有药物诱导版本的优势，允许时间控制，但它需要对靶基因进行工程化（“floxing”）。在这里，我们通过构建药物（他莫昔芬/米非司酮）诱导型 Cas9 和 Cpf1 CRISPR 效应器结合了这些优势。我们通过在携带 Tet 抑制的报告基因的细胞中使用 gRNA 将它们靶向 TetR，证明了它们的低背景活性和强大的药物激活。除了本身有用之外，这里生成的研究工具还将为制造更多的药物诱导效应蛋白铺平道路。