Crystal Structure of the RNA chaperone Hfq from Herbaspirillum seropedicae SMR1

Experimental Data Snapshot

  • Resolution: 2.63 Å
  • R-Value Free: 0.280 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.203 

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Structural characterization of the RNA chaperone Hfq from the nitrogen-fixing bacterium Herbaspirillum seropedicae SmR1.

Kadowaki, M.A.Iulek, J.Barbosa, J.A.R.G.Pedrosa, F.D.de Souza, E.M.Chubatsu, L.S.Monteiro, R.A.de Oliveira, M.A.Steffens, M.B.

(2011) Biochim Biophys Acta 1824: 359-365

  • DOI: https://doi.org/10.1016/j.bbapap.2011.11.002
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The RNA chaperone Hfq is a homohexamer protein identified as an E. coli host factor involved in phage Qβ replication and it is an important posttranscriptional regulator of several types of RNA, affecting a plethora of bacterial functions. Although twenty Hfq crystal structures have already been reported in the Protein Data Bank (PDB), new insights into these protein structures can still be discussed. In this work, the structure of Hfq from the β-proteobacterium Herbaspirillum seropedicae, a diazotroph associated with economically important agricultural crops, was determined by X-ray crystallography and small-angle X-ray scattering (SAXS). Biochemical assays such as exclusion chromatography and RNA-binding by the electrophoretic shift assay (EMSA) confirmed that the purified protein is homogeneous and active. The crystal structure revealed a conserved Sm topology, composed of one N-terminal α-helix followed by five twisted β-strands, and a novel π-π stacking intra-subunit interaction of two histidine residues, absent in other Hfq proteins. Moreover, the calculated ab initio envelope based on small-angle X-ray scattering (SAXS) data agreed with the Hfq crystal structure, suggesting that the protein has the same folding structure in solution.

  • Organizational Affiliation

    Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, PR, Brazil.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Protein hfq
A, B, C, D, E
A, B, C, D, E, F
79Herbaspirillum seropedicae SmR1Mutation(s): 0 
Gene Names: hfqHsero_2948
Find proteins for D8IZU6 (Herbaspirillum seropedicae (strain SmR1))
Explore D8IZU6 
Go to UniProtKB:  D8IZU6
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupD8IZU6
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on GOL

Download Ideal Coordinates CCD File 
C3 H8 O3
Experimental Data & Validation

Experimental Data

  • Resolution: 2.63 Å
  • R-Value Free: 0.280 
  • R-Value Work: 0.199 
  • R-Value Observed: 0.203 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 59.639α = 90
b = 65.323β = 105.47
c = 60.987γ = 90
Software Package:
Software NamePurpose
MAR345dtbdata collection
XDSdata reduction
XSCALEdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-01-04
    Type: Initial release
  • Version 1.1: 2012-01-11
    Changes: Database references
  • Version 1.2: 2017-06-21
    Changes: Database references
  • Version 1.3: 2024-02-28
    Changes: Data collection, Database references