Biological Assembly 1  

 3D View: Structure | Electron Density

Standalone Viewers  
Protein Workshop | Ligand Explorer

Global Symmetry: Cyclic - C2  (3D View)
Global Stoichiometry: Hetero 6-mer - A4B2 

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

Macromolecule Content

• Total Structure Weight: 156048.22 
• Atom Count: 9925 
• Residue Count: 1426 
• Unique protein chains: 2

4P6I

Crystal structure of the Cas1-Cas2 complex from Escherichia coli

• DOI: 10.2210/pdb4P6I/pdb

• Classification: HYDROLASE
• Organism(s): Escherichia coli (strain K12)
• Expression System: Escherichia coli BL21(DE3)


• Deposited: 2014-03-24 Released: 2014-05-07 
• Deposition Author(s): Nunez, J.K., Kranzusch, P.J., Noeske, J., Doudna, J.A.
• Funding Organization(s): National Science Foundation (United States) 

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.3 Å
• R-Value Free: 0.245 
• R-Value Work: 0.225 

Literature

Cas1-Cas2 complex formation mediates spacer acquisition during CRISPR-Cas adaptive immunity.

Nunez, J.K., Kranzusch, P.J., Noeske, J., Wright, A.V., Davies, C.W., Doudna, J.A.

(2014) Nat.Struct.Mol.Biol. 21: 528-534

• PubMed: 24793649 
• DOI: 10.1038/nsmb.2820


• PubMed Abstract: 
  

The initial stage of CRISPR-Cas immunity involves the integration of foreign DNA spacer segments into the host genomic CRISPR locus. The nucleases Cas1 and Cas2 are the only proteins conserved among all CRISPR-Cas systems, yet the molecular functions of these proteins during immunity are unknown. Here we show that Cas1 and Cas2 from Escherichia coli form a stable complex that is essential for spacer acquisition and determine the 2.3-Å-resolution crystal structure of the Cas1-Cas2 complex. Mutations that perturb Cas1-Cas2 complex formation disrupt CRISPR DNA recognition and spacer acquisition in vivo. Active site mutants of Cas2, unlike those of Cas1, can still acquire new spacers, thus indicating a nonenzymatic role of Cas2 during immunity. These results reveal the universal roles of Cas1 and Cas2 and suggest a mechanism by which Cas1-Cas2 complexes specify sites of CRISPR spacer integration.

---

Organizational Affiliation: 

Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA.

Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details
CRISPR-associated endoribonuclease Cas2	A, B	103	Escherichia coli (strain K12)	Mutation(s): 0  Gene Names: ygbF (cas2) EC: 3.1.-.-
Find proteins for P45956 (Escherichia coli (strain K12)) Go to UniProtKB:  P45956

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details
CRISPR-associated endonuclease Cas1	C, D, E, F	305	Escherichia coli (strain K12)	Mutation(s): 0  Gene Names: ygbT (cas1) EC: 3.1.-.-
Find proteins for Q46896 (Escherichia coli (strain K12)) Go to UniProtKB:  Q46896

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.3 Å
• R-Value Free: 0.245 
• R-Value Work: 0.225 
• Space Group: P 1 2₁ 1

Unit Cell:

Length (Å)	Angle (°)
a = 94.875	α = 90.00
b = 125.696	β = 102.74
c = 99.306	γ = 90.00

Software Package:

Software Name	Purpose
PHENIX	refinement

Structure Validation

Entry History & Funding Information

Deposition Data

• Deposited Date: 2014-03-24 
• Released Date: 2014-05-07 
• Deposition Author(s): Nunez, J.K., Kranzusch, P.J., Noeske, J., Doudna, J.A.

---

Funding Organization	Location	Grant Number
National Science Foundation (United States)	United States	1244557

Revision History 

• Version 1.0: 2014-05-07
  Type: Initial release
• Version 1.1: 2014-05-21
  Type: Database references
• Version 1.2: 2014-10-01
  Type: Database references
• Version 1.3: 2015-01-07
  Type: Database references
• Version 1.4: 2017-09-06
  Type: Author supporting evidence, Derived calculations, Other, Source and taxonomy