Bacterial virus anti-defence systems · sequence & structure resource

Encyclopaedia of Bacterial Virus Anti-Defence Systems


Protein: AcrIC3

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Overview

Mode of Action (MoA) AlphaFold 3 predicts a high confidence interaction between helicase/endonuclease Cas3 (https://www.ncbi.nlm.nih.gov/protein/UEM35119.1) and AcrIC3 (ipTM = 0.91, pTM = 0.90) and a moderate confidence interaction between Cas2 (https://www.ncbi.nlm.nih.gov/protein/UEM35125.1) and AcrIC3 (ipTM = 0.7, pTM = 0.56).
Evidence DMS3m phage was genetically engineered to carry the acrIC3 gene. This phage was then used to infect PAO1IC, a strain expressing the Type I-C CRISPR–Cas system from PaLML1 along with a crRNA targeting DMS3m. The engineered phage formed plaques on PAO1IC with an efficiency comparable to that on a non-targeting control strain, indicating strong anti-CRISPR activity. However, when Cas3 was fused to Cas8 — mimicking natural Cas3-Cas8 fusions to eliminate the normal recruitment interface — AcrIC3 no longer conferred protection, suggesting it normally blocks Cas3 recruitment to the Cascade complex. Binding it supported by computational structure modeling evidence (ECO_0006368).
MoA Category binds and inhibits host defence system (putative)
Subtype(s) of the defence system(s) inhibited by the protein Defence Subtype Pseudomonas aeruginosa type I-C CRISPR-Cas system
Relevant publication(s) DOI 10.1093/nar/gkab006
Other components of the anti-defence system Multicomponent System -
Known structure in PDB PDB ID -
Genome(s) encoding the protein Protein Source MGE in Pseudomonas aeruginosa
Defence system(s) inhibited by the protein Defences CRISPR-Cas

3D structure

AlphaFold 3 model.

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Feature viewer - predicted secondary structure

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Pfam annotations

No Pfam domains found

Sequence Viewer

Amino acid position: -

MSIQVTSTNGRTVNLEIELGSVVASSGQVKFMADKTDRGLESRFLVPEAGNRRIEVALTGRDLEAANALFSELAASVEATNEMYRELDAERAQINKALEG