The structure of the CRISPR-associated protein, Csa3, from Sulfolobus solfataricus at 1.8 angstrom resolution.

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.220 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.182 

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The Structure of the Crispr-Associated Protein Csa3 Provides Insight Into the Regulation of the Crispr/Cas System.

Lintner, N.G.Frankel, K.A.Tsutakawa, S.E.Alsbury, D.L.Copie, V.Young, M.J.Tainer, J.A.Lawrence, C.M.

(2011) J Mol Biol 405: 939

  • DOI: https://doi.org/10.1016/j.jmb.2010.11.019
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Adaptive immune systems have recently been recognized in prokaryotic organisms where, in response to viral infection, they incorporate short fragments of invader-derived DNA into loci called clustered regularly interspaced short palindromic repeats (CRISPRs). In subsequent infections, the CRISPR loci are transcribed and processed into guide sequences for the neutralization of the invading RNA or DNA. The CRISPR-associated protein machinery (Cas) lies at the heart of this process, yet many of the molecular details of the CRISPR/Cas system remain to be elucidated. Here, we report the first structure of Csa3, a CRISPR-associated protein from Sulfolobus solfataricus (Sso1445), which reveals a dimeric two-domain protein. The N-terminal domain is a unique variation on the dinucleotide binding domain that orchestrates dimer formation. In addition, it utilizes two conserved sequence motifs [Thr-h-Gly-Phe-(Asn/Asp)-Glu-X(4)-Arg and Leu-X(2)-Gly-h-Arg] to construct a 2-fold symmetric pocket on the dimer axis. This pocket is likely to represent a regulatory ligand-binding site. The N-terminal domain is fused to a C-terminal MarR-like winged helix-turn-helix domain that is expected to be involved in DNA recognition. Overall, the unique domain architecture of Csa3 suggests a transcriptional regulator under allosteric control of the N-terminal domain. Alternatively, Csa3 may function in a larger complex, with the conserved cleft participating in protein-protein or protein-nucleic acid interactions. A similar N-terminal domain is also identified in Csx1, a second CRISPR-associated protein family of unknown function.

  • Organizational Affiliation

    Thermal Biology Institute, Montana State University, Bozeman, MT 59717, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
244Saccharolobus solfataricus P2Mutation(s): 0 
Gene Names: csa3SSO1445
Find proteins for Q97Y88 (Saccharolobus solfataricus (strain ATCC 35092 / DSM 1617 / JCM 11322 / P2))
Explore Q97Y88 
Go to UniProtKB:  Q97Y88
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ97Y88
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on PEG

Download Ideal Coordinates CCD File 
C4 H10 O3
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
Query on MSE
A, B
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.220 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.182 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 53.426α = 90
b = 89.853β = 90
c = 102.577γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-09-22
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance