Biological Assembly 1  

Global Symmetry: Cyclic - C2  (3D View)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 1 assigned by authors and generated by PISA (software)

Biological Assembly Evidence: gel filtration

Biological Assembly 2  

Global Symmetry: Cyclic - C2  (3D View)
Global Stoichiometry: Homo 2-mer - A2 

Biological assembly 2 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 36.36 kDa 
• Atom Count: 2,415 
• Modelled Residue Count: 279 
• Deposited Residue Count: 318 
• Unique protein chains: 1

 6AS4

Structure of a phage anti-CRISPR protein

• PDB DOI:  https://doi.org/10.2210/pdb6AS4/pdb

• Classification: VIRAL PROTEIN
• Organism(s): Pseudomonas phage JBD5
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): No 


• Deposited: 2017-08-23 Released: 2017-12-20 
• Deposition Author(s): Shah, M., Calmettes, C., Pawluk, A., Mejdani, M., Davidson, A.R., Maxwell, K.L., Moraes, T.F.
• Funding Organization(s): Canadian Institutes of Health Research (CIHR)

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.00 Å
• R-Value Free: 0.228 
• R-Value Work: 0.190 
• R-Value Observed: 0.192 

Literature

Disabling a Type I-E CRISPR-Cas Nuclease with a Bacteriophage-Encoded Anti-CRISPR Protein.

Pawluk, A., Shah, M., Mejdani, M., Calmettes, C., Moraes, T.F., Davidson, A.R., Maxwell, K.L.

(2017) mBio 8

• PubMed: 29233895 
• DOI: https://doi.org/10.1128/mBio.01751-17
• Primary Citation of Related Structures:  
  6ARZ, 6AS3, 6AS4


• PubMed Abstract: 
  

CRISPR (clustered regularly interspaced short palindromic repeat)-Cas adaptive immune systems are prevalent defense mechanisms in bacteria and archaea. They provide sequence-specific detection and neutralization of foreign nucleic acids such as bacteriophages and plasmids. One mechanism by which phages and other mobile genetic elements are able to overcome the CRISPR-Cas system is through the expression of anti-CRISPR proteins. Over 20 different families of anti-CRISPR proteins have been described, each of which inhibits a particular type of CRISPR-Cas system. In this work, we determined the structure of type I-E anti-CRISPR protein AcrE1 by X-ray crystallography. We show that AcrE1 binds to the CRISPR-associated helicase/nuclease Cas3 and that the C-terminal region of the anti-CRISPR protein is important for its inhibitory activity. We further show that AcrE1 can convert the endogenous type I-E CRISPR system into a programmable transcriptional repressor. IMPORTANCE The CRISPR-Cas immune system provides bacteria with resistance to invasion by potentially harmful viruses, plasmids, and other foreign mobile genetic elements. This study presents the first structural and mechanistic insight into a phage-encoded protein that inactivates the type I-E CRISPR-Cas system in Pseudomonas aeruginosa The interaction of this anti-CRISPR protein with the CRISPR-associated helicase/nuclease proteins Cas3 shuts down the CRISPR-Cas system and protects phages carrying this gene from destruction. This interaction also allows the repurposing of the endogenous type I-E CRISPR system into a programmable transcriptional repressor, providing a new biotechnological tool for genetic studies of bacteria encoding this type I-E CRISPR-Cas system.

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Organizational Affiliation: 

Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada [e-mail] [e-mail].

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
NHis AcrE1 anti-crispr protein	A, B, C	106	Pseudomonas phage JBD5	Mutation(s): 0  Gene Names: JBD5_034
UniProt
Find proteins for L7P7L6 (Pseudomonas phage JBD5) Explore L7P7L6  Go to UniProtKB:  L7P7L6

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.00 Å
• R-Value Free: 0.228 
• R-Value Work: 0.190 
• R-Value Observed: 0.192 
• Space Group: C 1 2 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 96.74	α = 90
b = 63.53	β = 100.34
c = 59.46	γ = 90

Software Package:

Software Name	Purpose
XSCALE	data scaling
PHENIX	refinement
PDB_EXTRACT	data extraction
XDS	data processing
PHASER	phasing

Structure Validation

Entry History & Funding Information

Deposition Data

• Released Date: 2017-12-20 
Deposition Author(s): Shah, M., Calmettes, C., Pawluk, A., Mejdani, M., Davidson, A.R., Maxwell, K.L., Moraes, T.F.

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Funding Organization	Location	Grant Number
Canadian Institutes of Health Research (CIHR)	Canada	MOP-130482
Canadian Institutes of Health Research (CIHR)	Canada	MOP-136845

Revision History  

• Version 1.0: 2017-12-20
  Type: Initial release
  
• Version 1.1: 2017-12-27
  Changes: Database references
• Version 1.2: 2020-01-08
  Changes: Author supporting evidence