期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：11
页码：3570-3575
DOI：10.1073/pnas.1420294112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceThe clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 nuclease (Cas9) system has recently emerged as an efficient and versatile tool for genome editing in various organisms. However, its targeting capability and multiplex editing efficiency are often limited by the guide RNA (gRNA)-expressing device. This study demonstrates a general strategy and platform for precise processing and efficient production of numerous gRNAs in vivo from a synthetic polycistronic gene via the endogenous tRNA-processing system. This strategy is shown to significantly increase CRISPR/Cas9 multiplex editing capability and efficiency in plants and is expected to have broad applications for small RNA expression and genome engineering. The clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 nuclease (Cas9) system is being harnessed as a powerful tool for genome engineering in basic research, molecular therapy, and crop improvement. This system uses a small guide RNA (gRNA) to direct Cas9 endonuclease to a specific DNA site; thus, its targeting capability is largely constrained by the gRNA-expressing device. In this study, we developed a general strategy to produce numerous gRNAs from a single polycistronic gene. The endogenous tRNA-processing system, which precisely cleaves both ends of the tRNA precursor, was engineered as a simple and robust platform to boost the targeting and multiplex editing capability of the CRISPR/Cas9 system. We demonstrated that synthetic genes with tandemly arrayed tRNA-gRNA architecture were efficiently and precisely processed into gRNAs with desired 5' targeting sequences in vivo, which directed Cas9 to edit multiple chromosomal targets. Using this strategy, multiplex genome editing and chromosomal-fragment deletion were readily achieved in stable transgenic rice plants with a high efficiency (up to 100%). Because tRNA and its processing system are virtually conserved in all living organisms, this method could be broadly used to boost the targeting capability and editing efficiency of CRISPR/Cas9 toolkits.
