dCas9
Pronunciation: dee-kaz-NINE
Also written as: dCas9 — dead Cas9
A catalytically inactive form of Cas9 that retains DNA-binding capability but lacks nuclease activity, used to recruit transcriptional effectors to specific genomic loci.
Full Definition
Deactivated Cas9 (dCas9) carries mutations in both nuclease domains (D10A in the RuvC domain and H840A in the HNH domain), abolishing its ability to cleave DNA while preserving its RNA-guided DNA-binding activity. When fused to transcriptional activators (e.g., VP64, VPR) or repressors (e.g., KRAB), dCas9 forms the basis of CRISPRa and CRISPRi systems for gene regulation. Editors should use the mixed-case convention 'dCas9' (lowercase 'd' for dead/deactivated). Distinguish from nCas9 (nickase Cas9), which retains one functional nuclease domain.
Usage
Usage note: Mixed case: lowercase 'd', uppercase 'C': 'dCas9'. Not 'dCAS9' or 'Dcas9'. Distinguish from nCas9 (one active nuclease domain) and from full Cas9 (both domains active).
In Context
- "dCas9 fused to a KRAB repressor domain was used to silence the target gene without permanent genomic alteration." — Methods section
- "The authors had written 'DCas9' throughout; all instances were corrected to 'dCas9'." — Proofreading note