Structural insights into Cas13b-guided CRISPR RNA maturation and recognition
Dear EditorCRISPR-Cas (clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins) systems are RNA-guided adaptive immune systems in prokaryotes.1,2 Class 2 CRISPR-Cas systems (including type Ⅱ,Ⅴ,and Ⅵ) involve large single effector proteins in complex with crRNA for interference.3,4 The type Ⅱ and Ⅴ effectors,such as Cas9 and Cas12a,have been engineered into powerful tools for genome editing.The type Ⅵ system encompasses RNA-guided RNases.Its effectors Cas13a,Cas13b and Cas13d are capable of both precursor CRISPR RNA (pre-crRNA) processing and target RNA cleavage,which protect the host from phage attacks.5-7 Once bound to a target RNA,they are activated,switching on a non-specific RNase activity.Moreover,they have been utilized to target and edit RNA as programmable RNA-binding modules.6,8-12 Although related to Cas13a and Cas13d,Cas1 3b possesses many distinctive features.These include the lack of significant sequence similarity with Cas13a and Cas13d,disparate crRNA repeat region,double-sided protospacer flanking sequence (PFS)-dependent target RNA cleavage.5-8,13
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the Ministry of Science and Technology of China grants 2014CB910400 and the National Nature Science Foundation of China grants 31770948,31570875 and 81590761.We thank Fujian Normal University for financial support.The diffraction data were collected at the beamline BL-17U1 of Shanghai Synchrotron Radiation Facility SSRF.We thank Gonghong Wei and Zhaoqing Luo for discussions.We thank Wei Yang and Zhijian J.Chen for critical review of the manuscript
2019-01-12（万方平台首次上网日期，不代表论文的发表时间）
共4页
1198-1201
