Direct CRISPR spacer acquisition from RNA by a natural reverse transcriptase–Cas1 fusion protein

作者：Sukrit Silas, Georg Mohr, David J. Sidote, Laura M. Markham, Antonio Sánchez-Amat, Devaki Bhaya, Alan M. Lambowitz, Andrew Fire · 发表于：Science · 年份：2016 · DOI：10.1126/science.aad4234 · 被引用次数：220 · 研究领域：CRISPR and Genetic Engineering、Insect symbiosis and bacterial influences、Evolution and Genetic Dynamics

CRISPR systems mediate adaptive immunity in diverse prokaryotes. CRISPR-associated Cas1 and Cas2 proteins have been shown to enable adaptation to new threats in type I and II CRISPR systems by the acquisition of short segments of DNA (spacers) from invasive elements. In several type III CRISPR systems, Cas1 is naturally fused to a reverse transcriptase (RT). In the marine bacterium Marinomonas mediterranea (MMB-1), we showed that a RT-Cas1 fusion protein enables the acquisition of RNA spacers in vivo in a RT-dependent manner. In vitro, the MMB-1 RT-Cas1 and Cas2 proteins catalyze the ligation of RNA segments into the CRISPR array, which is followed by reverse transcription. These observations outline a host-mediated mechanism for reverse information flow from RNA to DNA.