Lucas B. Harrington, David Burstein, Janice S. Chen, David Paez-Espino, Enbo Ma, Isaac P. Witte, Joshua C. Cofsky, Nikos C. Kyrpides, Jillian F. Banfield, Jennifer A. Doudna
SCIENCE 18 Oct 2018: eaav4294 - DOI: 10.1126/science.aav4294
Abstract
CRISPR-Cas systems provide microbes with adaptive immunity to infectious nucleic acids and are widely employed as genome editing tools. These tools utilize RNA-guided Cas proteins whose large size (950–1400 amino acids) has been considered essential to their specific DNA- or RNA-targeting activities. Here we present a set of CRISPR-Cas systems from uncultivated archaea that contain Cas14, a family of exceptionally compact RNA-guided nucleases (400–700 amino acids). Despite their small size, Cas14 proteins are capable of targeted single-stranded DNA (ssDNA) cleavage without restrictive sequence requirements. Moreover, target recognition by Cas14 triggers non-specific cutting of ssDNA molecules, an activity that enables high-fidelity SNP genotyping (Cas14-DETECTR). Metagenomic data show that multiple CRISPR-Cas14 systems evolved independently and suggest a potential evolutionary origin of single-effector CRISPR-based adaptive immunity.
See: http://science.sciencemag.org/content/early/2018/10/17/science.aav4294.long
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