Precise DNA cleavage using CRISPR-SpRYgests
作者：Kathleen A. Christie, Jimmy A. Guo, Rachel A. Silverstein, Roman M. Doll, Megumu Mabuchi, Hannah E. Stutzman, Jiecong Lin, Linyuan Ma, Russell T. Walton, Luca Pinello, G. Brett Rob
Nature Biotechnology：2022/10/06
Methods for in vitro DNA cleavage and molecular cloning remain unable to precisely cleave DNA directly adjacent to bases of interest. Restriction enzymes (REs) must bind specific motifs, whereas wild-type CRISPR–Cas9 or CRISPR–Cas12 nucleases require protospacer adjacent motifs (PAMs). Here we explore the utility of our previously reported near-PAMless SpCas9 variant, named SpRY, to serve as a universal DNA cleavage tool for various cloning applications. By performing SpRY DNA digests (SpRYgests) using more than 130 guide RNAs (gRNAs) sampling a wide diversity of PAMs, we discovered that SpRY is PAMless in vitro and can cleave DNA at practically any sequence, including sites refractory to cleavage with wild-type SpCas9. We illustrate the versatility and effectiveness of SpRYgests to improve the precision of several cloning workflows, including those not possible with REs or canonical CRISPR nucleases. We also optimize a rapid and simple one-pot gRNA synthesis protocol to streamline SpRYgest implementation. Together, SpRYgests can improve various DNA engineering applications that benefit from precise DNA breaks.
CRISPR-Cas基因編輯的一個主要限制在于，首先需要識別出一個短序列，叫做前間區(qū)序列鄰近基序（PAM），因此只能在特定基序的附近切割DNA。而最近，在一項發(fā)表在《自然·生物技術(shù)》的研究中，科學(xué)家發(fā)現(xiàn)一種方法，可以突破PAM的限制。
