Laboratory of Microbiology, Wageningen University, Netherlands.
Cold Spring Harb Perspect Biol. 2012 Jun 1;4(6):a003657. doi: 10.1101/cshperspect.a003657.
The CRISPR/Cas system in prokaryotes provides resistance against invading viruses and plasmids. Three distinct stages in the mechanism can be recognized. Initially, fragments of invader DNA are integrated as new spacers into the repetitive CRISPR locus. Subsequently, the CRISPR is transcribed and the transcript is cleaved by a Cas protein within the repeats, generating short RNAs (crRNAs) that contain the spacer sequence. Finally, crRNAs guide the Cas protein machinery to a complementary invader target, either DNA or RNA, resulting in inhibition of virus or plasmid proliferation. In this article, we discuss our current understanding of this fascinating adaptive and heritable defense system, and describe functional similarities and differences with RNAi in eukaryotes.
原核生物中的 CRISPR/Cas 系统为其抵抗入侵的病毒和质粒提供了抗性。该机制可分为三个不同阶段。首先，入侵者 DNA 的片段整合到重复的 CRISPR 基因座中作为新的间隔序列。随后，CRISPR 被转录，并且在重复序列内的 Cas 蛋白对转录本进行切割，生成含有间隔序列的短 RNA（crRNA）。最后，crRNA 引导 Cas 蛋白复合物到互补的入侵者靶标，无论是 DNA 还是 RNA，从而抑制病毒或质粒的增殖。在本文中，我们讨论了对这一迷人的适应性和遗传性防御系统的现有理解，并描述了与真核生物中 RNAi 的功能相似性和差异性。
