8HI1

Streptococcus thermophilus Cas1-Cas2- prespacer ternary complex

Summary for 8HI1

• Entry DOI: 10.2210/pdb8hi1/pdb
• EMDB information: 34809
• Descriptor: CRISPR-associated endonuclease Cas1, Type I-E CRISPR-associated endoribonuclease Cas2, DNA (26-MER), ... (4 entities in total)
• Functional Keywords: crispr, cas, adaptation, immune system
• Biological source: Streptococcus thermophilus DGCC 7710; More
• Total number of polymer chains: 8
• Total formula weight: 193530.10

Authors

Chen, Q.,Luo, Y. (deposition date: 2022-11-18, release date: 2023-09-13, Last modification date: 2025-07-02)

Primary citation

Tang, D.,Jia, T.,Luo, Y.,Mou, B.,Cheng, J.,Qi, S.,Yao, S.,Su, Z.,Yu, Y.,Chen, Q.
DnaQ mediates directional spacer acquisition in the CRISPR-Cas system by a time-dependent mechanism.
Innovation (N Y), 4:100495-100495, 2023

PubMed Abstract: In the spacer acquisition stage of CRISPR-Cas immunity, spacer orientation and protospacer adjacent motif (PAM) removal are two prerequisites for functional spacer integration. Cas4 has been implicated in both processing the prespacer and determining the spacer orientation. In Cas4-lacking systems, host 3'-5' DnaQ family exonucleases were recently reported to play a Cas4-like role. However, the molecular details of DnaQ functions remain elusive. Here, we characterized the spacer acquisition of the adaptation module of the type I-E system, in which a DnaQ domain naturally fuses with Cas2. We presented X-ray crystal structures and cryo-electron microscopy structures of this adaptation module. Our biochemical data showed that DnaQ trimmed PAM-containing and PAM-deficient overhangs with different efficiencies. Based on these results, we proposed a time-dependent model for DnaQ-mediated spacer acquisition to elucidate PAM removal and spacer orientation determination in Cas4-lacking CRISPR-Cas systems.

PubMed: 37663930
DOI: 10.1016/j.xinn.2023.100495

Experimental method

ELECTRON MICROSCOPY (3.09 Å)