Structure-based mechanistic insights into PAM-dependent spacer acquisition for incorporation into the CRISPR array

International Conference on Applied Crystallography

October 17-19, 2016 Houston, USA

Yanli Wang, Jiazhi Li, Hongtu Zhao, Gang Sheng, Min Wang, Maolu Yin and Jiuyu Wang

Chinese Academy of Sciences, China

Scientific Tracks Abstracts: J Material Sci Eng

Abstract :

Bacteria obtain a memory of viral invaders by incorporating their DNA sequence elements into the host CRISPR locus, generating a new 33-nt spacer within the CRISPR array. We report on the crystal structure of a Cas1-Cas2-dual-forked DNA complex in efforts towards understanding how the protospacer is selected for insertion into the CRISPR locus. Our structure of the complex reveals a protospacer DNA containing a 23-bp duplex bracketed by tyrosine residues, together with anchored flanking 3�-overhang segments. The complementary PAM sequence in the 3�-overhangs are recognized by Cas1a catalytic subunits in a base-specific manner for protospacer selection and subsequent cleavage at positions 5-nts from the duplex boundary, thereby generating a 33- nt DNA intermediate for incorporation into the CRISPR array. Upon protospacer binding, the Cas1-Cas2 complex undergoes a significant conformational change, generating a flat surface conducive to proper protospacer recognition. Overall, our studies reveal unanticipated structure-based mechanistic insights into PAM-dependent spacer acquisition.

Biography :

Yanli Wang has completed her PhD from University of Science and Technology of China and Post-doctoral studies from Memorial Sloan-Kettering Cancer Center. She is a Principle Investigator of Institute of Biophysics, Chinese Academy of Sciences. She has published more than 25 papers in reputed journals and has been serving as an Editorial Board Member of Non-Coding RNA.

Email: ylwang@sun5.ibp.ac.cn