Bacterial virus anti-defence systems · sequence & structure resource

Encyclopaedia of Bacterial Virus Anti-Defence Systems


Protein: AcrIIIB2

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Overview

Mode of Action (MoA) blocks the dissociation of cleaved target RNA from Cmr-α, inhibiting Cmr-α turnover and thereby suppressing Cas10 activities.
Evidence The gene gp40 from SIRV3 (AcrIIIB2) was used to replace the known Acr gene (acrIIIB1) in SIRV2. The recombinant virus SIRV2ΔacrIIIB1+gp40 was able to infect S. islandicus LAL14/1, which has a functional type III-B CRISPR-Cas system. This restored infectivity demonstrated that gp40 compensates for the loss of acrIIIB1, confirming its role as an anti-CRISPR protein. Pull-down assays with HA-tagged AcrIIIB2 revealed direct interaction with the Cmr-a complex, a type III-B effector (ECO_0006074).
MoA Category binds and inhibits host defence system
Subtype(s) of the defence system(s) inhibited by the protein Defence Subtype Sulfolobus islandicus type III-B CRISPR-Cas
Relevant publication(s) DOI 10.1016/j.chom.2023.10.003
Other components of the anti-defence system Multicomponent System -
Known structure in PDB PDB ID -
Genome(s) encoding the protein Protein Source Sulfolobus islandicus rod-shaped virus 3 isolate SIRV3
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: -

MSSTCNPITSFGKLLNKIAKQSLISSQLWNDIIQDLYTAYSVYKYINTSLQYQFQYEFSYGNLNTLNSLFNNLYFYIFNQKPYQFVPLINASPGLPLTVNYMNNLIKAITKLANENNITLAKPLNFVQSNEIVKSRKFNDIIYVINQFLTFDFNSYFLLDCYGSIFSNLVNSQSAFLNILIDNPSQNISTNNIYIKNLIINYLKTVLNFYGNSAIDNFLIGNHQPPYLAVVGSSIYLYNNSAINNLIIYENYGYIQLNDNSYIQNLIISINNATIELNDNAIIENLICKQNYGQIQINGNAQIINNNCQ