4AN8

Structure of Thermus thermophilus CasA (Cse1)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.196 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Mechanism of Foreign DNA Selection in a Bacterial Adaptive Immune System.

Sashital, D.G.Wiedenheft, B.Doudna, J.A.

(2012) Mol.Cell 46: 606

  • DOI: 10.1016/j.molcel.2012.03.020

  • PubMed Abstract: 
  • In bacterial and archaeal CRISPR immune pathways, DNA sequences from invading bacteriophage or plasmids are integrated into CRISPR loci within the host genome, conferring immunity against subsequent infections. The ribonucleoprotein complex Cascade u ...

    In bacterial and archaeal CRISPR immune pathways, DNA sequences from invading bacteriophage or plasmids are integrated into CRISPR loci within the host genome, conferring immunity against subsequent infections. The ribonucleoprotein complex Cascade utilizes RNAs generated from these loci to target complementary "nonself" DNA sequences for destruction, while avoiding binding to "self" sequences within the CRISPR locus. Here we show that CasA, the largest protein subunit of Cascade, is required for nonself target recognition and binding. Combining a 2.3 Å crystal structure of CasA with cryo-EM structures of Cascade, we have identified a loop that is required for viral defense. This loop contacts a conserved three base pair motif that is required for nonself target selection. Our data suggest a model in which the CasA loop scans DNA for this short motif prior to target destabilization and binding, maximizing the efficiency of DNA surveillance by Cascade.


    Organizational Affiliation

    Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
CSE1
A, B
506Thermus thermophilus (strain HB8 / ATCC 27634 / DSM 579)Mutation(s): 0 
Gene Names: cse1 (casA)
Find proteins for Q53VY1 (Thermus thermophilus (strain HB8 / ATCC 27634 / DSM 579))
Go to UniProtKB:  Q53VY1
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ACT
Query on ACT

Download SDF File 
Download CCD File 
A, B
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Free: 0.247 
  • R-Value Work: 0.196 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 94.360α = 90.00
b = 48.110β = 97.03
c = 129.780γ = 90.00
Software Package:
Software NamePurpose
PHENIXrefinement
XDSdata reduction
autoSHARPphasing
XSCALEdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-05-02
    Type: Initial release
  • Version 1.1: 2012-06-20
    Type: Other