Dear Editor, Prokaryotes and viruses have been engaged in an evolutionary struggle for billions of years.1 Bacteria and archaea employ clustered regularly interspaced short palindromic repeats(CRISPR)-CRISPR-associated(Cas)adaptive immune systems to protect against viral infection.2 The CRISPR-Cas locus consists of two parts:CRISPR and Cas genes.According to the latest phylogenetic classification,the CRISPR-Cas system can be divided into two classes,which can be further subdivided into six types.3 Class 1 CRISPR-Cas systems are characterized by a multiprotein effector,and consist of type Ⅰ,Ⅲ,and Ⅳ CRISPR-Cas systems.Class 2 CRISPR-Cas systems feature a single nuclease protein,and consist of type Ⅱ,Ⅴ,and Ⅵ CRISPR-Cas systems.The type Ⅱ Cas9 and type Ⅴ Cas12 systems have been engineered as genome editing tools,and they have been successfully applied in a broad range of organisms.4,5 Compared to Cas9,the type ⅥCas13 system exhibits RNA-guided RNase activity and the property of nonspecific cutting.6 Recently,a new subtype of CRISPR-Cas,type Ⅲ-E,3 has been identified and named gRAMP7 or Cas7-11.8 Unlike the traditional effectors of the type Ⅲ CRISPR-Cas system,gRAMP is a single effector protein with four Cas7 proteins and one Cas11 protein fused together.Given its unique architecture and specific cleavage activity,gRAMP is expected to be engineered as a powerful RNA editing tool.8 Interestingly,a gene encoding the caspase-like peptidase TPR-CHAT often co-occurs with gRAMP gene clusters.3 TPR-CHAT interacts directly with gRAMP,7 indicat-ing a functional relationship between the CRISPR-Cas system and caspase peptidase.However,the exact mechanism of the recognition and cleavage of target ssRNA by gRAMP from Candidatus"Scalindua brodae"(Sb-gRAMP),7 as well as the molecular architecture of the CRISPR-guided caspase complex,remain unclear.

Shuo Wang;Minghui Guo;Yuwei Zhu;Zhiying Lin;Zhiwei Huang

HIT Center for Life Sciences,School of Life Science and Technology,Harbin Institute of Technology,Harbin,Heilongjiang,China;Westlake Center for Genome Editing,Westlake Laboratory of Life Sciences and Biomedicine,School of Life Sciences,Westlake University,Hangzhou,Zhejiang,China

细胞研究（英文版）

[1]Shuo Wang;Minghui Guo;Yuwei Zhu;Zhiying Lin;Zhiwei Huang-.Cryo-EM structure of the type Ⅲ-E CRISPR-Cas effector gRAMP in complex with TPR-CHAT)[J].细胞研究（英文版）,2022(12):1128-1131

gRAMP, Prokaryotes,gRAMP7,Cas7,Cas11,ssRNA,Scalindua,brodae

Cryo,EM,structure,CRISPR,complex,TPR,CHAT,Dear,Editor,viruses,have,been,engaged,evolutionary,struggle,billions,years,Bacteria,archaea,employ,clustered,regularly,interspaced,short,palindromic,repeats,associated,adaptive,immune,systems,protect,against,viral,infection,locus,consists,two,parts,genes,According,latest,phylogenetic,classification,can,into,classes,which,further,subdivided,six,types,Class,characterized,by,multiprotein,feature,single,nuclease,Cas9,Cas12,engineered,genome,editing,tools,they,successfully,applied,broad,range,organisms,Compared,Cas13,exhibits,guided,RNase,activity,property,nonspecific,cutting,Recently,new,subtype,has,identified,named,Unlike,traditional,effectors,four,proteins,one,fused,together,Given,unique,architecture,cleavage,expected,powerful,Interestingly,encoding,caspase,peptidase,often,occurs,clusters,interacts,directly,indicat,functional,relationship,between,However,exact,mechanism,recognition,target,from,Candidatus,Sb,well,molecular,remain,unclear

0.483141