Crystal structure of Cas1 in complex with branched DNA  

作　　者：Jing Yang Jiazhi Li Jiuyu Wang Gang Sheng Min Wang Hongtu Zhao Yanhua Yang Yanli Wang 

机构地区：[1]Institute of Life Sciences,Jiangsu University,Zhenjiang 212013,China [2]Key Laboratory of RNA Biology,CAS Center for Excellence in Biomacromolecules,Institute of Biophysics,Chinese Academy of Sciences,Beijing 100101,China [3]University of Chinese Academy of Sciences,Beijing 100049,China [4]National Laboratory of Biomacromolecules,CAS Center for Excellence in Biomacromolecules,Institute of Biophysics,Chinese Academy of Sciences,Beijing 100101,China

出　　处：《Science China(Life Sciences)》2020年第4期516-528,共13页中国科学（生命科学英文版）

基　　金：The research was funded by the National Natural Science Foundation of China(31630015,31725008);the Chinese Academy of Sciences(QYZDY-SSW-SMC021).

摘　　要：Cas1 is a key component of the CRISPR adaptation complex,which captures and integrates foreign DNA into the CRISPR array,resulting in the generation of new spacers.We have determined crystal structures of Thermus thermophilus Cas1 involved in new spacer acquisition both in complex with branched DNA and in the free state.Cas1 forms an asymmetric dimer without DNA.Conversely,two asymmetrical dimers bound to two branched DNAs result in the formation of a DNA-mediated tetramer,dimer of structurally asymmetrical dimers,in which the two subunits markedly present different conformations.In the DNA binding complex,the N-terminal domain adopts different orientations with respect to the C-terminal domain in the two monomers that form the dimer.Substrate binding triggers a conformational change in the loop 164–177 segment.This loop is also involved in the 3′fork arm and 5′fork arm strand recognition in monomer A and B,respectively.This study provides important insights into the molecular mechanism of new spacer adaptation.Cas1 is a key component of the CRISPR adaptation complex, which captures and integrates foreign DNA into the CRISPR array,resulting in the generation of new spacers. We have determined crystal structures of Thermus thermophilus Cas1 involved in new spacer acquisition both in complex with branched DNA and in the free state. Cas1 forms an asymmetric dimer without DNA.Conversely, two asymmetrical dimers bound to two branched DNAs result in the formation of a DNA-mediated tetramer, dimer of structurally asymmetrical dimers, in which the two subunits markedly present different conformations. In the DNA binding complex, the N-terminal domain adopts different orientations with respect to the C-terminal domain in the two monomers that form the dimer. Substrate binding triggers a conformational change in the loop 164–177 segment. This loop is also involved in the 3′ fork arm and 5′ fork arm strand recognition in monomer A and B, respectively. This study provides important insights into the molecular mechanism of new spacer adaptation.

关 键 词：CRISPR CAS protein Cas1 ADAPTATION DNA integration structure PROTEIN-DNA COMPLEX 

分 类 号：Q617[生物学—生物物理学]