This study describes the strong anti-CRISPR activity of the bacterial AcrIIA4 protein in Nicotiana benthamiana, a model plant used as molecular farming platform. The results demonstrate that AcrIIA4 abolishes site-directed mutagenesis in leaves when transiently co-expressed with CRISPR/Cas9. We also show that AcrIIA4 represses CRISPR/dCas9-based transcriptional activation (CRISPRa) of both reporter and endogenous genes in a highly efficient, dose-dependent manner. Furthermore, the fusion of an auxin degron to AcrIIA4 results in auxin-regulated activation of a downstream reporter gene. The strong anti-Cas9 activity of AcrIIA4 reported here opens new possibilities for customized control of gene editing and gene expression in plants.

中文翻译：

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AcrIIA4在植物中的强大且可调的抗CRISPR / Cas9活性

这项研究描述了本生烟草（Nicotiana benthamiana）中的细菌AcrIIA4蛋白具有很强的抗CRISPR活性，该烟草是一种用作分子耕种平台的模型植物。结果表明，当与CRISPR / Cas9瞬时共表达时，AcrIIA4消除了叶片中的定点诱变。我们还显示，AcrIIA4以高效，剂量依赖的方式抑制记者和内源基因的基于CRISPR / dCas9的转录激活（CRISPRa）。此外，生长素地龙与AcrIIA4的融合导致生长素调节下游报告基因的激活。此处报道的AcrIIA4强大的抗Cas9活性为定制控制植物中的基因编辑和基因表达提供了新的可能性。