+検索条件
-Structure paper
| タイトル | Structural basis of a dual-function type II-B CRISPR-Cas9. |
|---|---|
| ジャーナル・号・ページ | Nucleic Acids Res, Vol. 53, Issue 12, Year 2025 |
| 掲載日 | 2025年6月20日 |
著者 | Grace N Hibshman / David W Taylor / ![]() |
| PubMed 要旨 | Cas9 from Streptococcus pyogenes (SpCas9) revolutionized genome editing by enabling programmable DNA cleavage guided by an RNA. However, SpCas9 tolerates mismatches in the DNA-RNA duplex, which can ...Cas9 from Streptococcus pyogenes (SpCas9) revolutionized genome editing by enabling programmable DNA cleavage guided by an RNA. However, SpCas9 tolerates mismatches in the DNA-RNA duplex, which can lead to deleterious off-target editing. Here, we reveal that Cas9 from Francisella novicida (FnCas9) possesses a unique structural feature-the REC3 clamp-that underlies its intrinsic high-fidelity DNA targeting. Through kinetic and structural analyses, we show that the REC3 clamp forms critical contacts with the PAM-distal region of the R-loop, thereby imposing a novel checkpoint during enzyme activation. Notably, F. novicida encodes a noncanonical small CRISPR-associated RNA (scaRNA) that enables FnCas9 to repress an endogenous bacterial lipoprotein gene, subverting host immune detection. Structures of FnCas9 with scaRNA illustrate how partial R-loop complementarity hinders REC3 clamp docking and prevents cleavage in favor of transcriptional repression. The REC3 clamp is conserved across type II-B CRISPR-Cas9 systems, pointing to a potential path for engineering precise genome editors or developing novel antibacterial strategies. These findings reveal the molecular basis of heightened specificity and virulence enabled by FnCas9, with broad implications for biotechnology and therapeutic development. |
リンク | Nucleic Acids Res / PubMed:40613710 / PubMed Central |
| 手法 | EM (単粒子) |
| 解像度 | 2.6 - 3.0 Å |
| 構造データ | EMDB-48052, PDB-9ehf: EMDB-48053, PDB-9ehg: EMDB-48054, PDB-9ehh: EMDB-48062, PDB-9ehr: EMDB-48069, PDB-9ehw: EMDB-48070, PDB-9ehx: EMDB-49074, PDB-9n6t: |
| 化合物 | ![]() ChemComp-MG: |
| 由来 |
|
キーワード | Hydrolase/DNA/RNA / Francisella novicida-Cas9 / CRISPR / Cas9 / IMMUNE SYSTEM / Hydrolase-DNA-RNA complex / Hydrolase/RNA/DNA / Hydrolase-RNA-DNA complex |
ムービー
コントローラー
構造ビューア
万見文献について



著者
リンク














francisella tularensis subsp. novicida (バクテリア)
homo sapiens (ヒト)
キーワード