Structure of Legionella fallonii DegQ (wt)

Experimental Data Snapshot

  • Resolution: 2.15 Å
  • R-Value Free: 0.251 
  • R-Value Work: 0.211 
  • R-Value Observed: 0.213 

Starting Model: experimental
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The Legionella HtrA homologue DegQ is a self-compartmentizing protease that forms large 12-meric assemblies.

Wrase, R.Scott, H.Hilgenfeld, R.Hansen, G.

(2011) Proc Natl Acad Sci U S A 108: 10490-10495

  • DOI: https://doi.org/10.1073/pnas.1101084108
  • Primary Citation of Related Structures:  
    3PV2, 3PV3, 3PV4, 3PV5

  • PubMed Abstract: 

    Proteases of the HtrA family are key factors dealing with folding stress in the periplasmatic compartment of prokaryotes. In Escherichia coli, the well-characterized HtrA family members DegS and DegP counteract the accumulation of unfolded outer-membrane proteins under stress conditions. Whereas DegS serves as a folding-stress sensor, DegP is a chaperone-protease facilitating refolding or degradation of defective outer-membrane proteins. Here, we report the 2.15-Å-resolution crystal structure of the second major chaperone-protease of the periplasm, DegQ from Legionella fallonii. DegQ assembles into large, cage-like 12-mers that form independently of unfolded substrate proteins. We provide evidence that 12-mer formation is essential for the degradation of substrate proteins but not for the chaperone activity of DegQ. In the current model for the regulation of periplasmatic chaperone-proteases, 6-meric assemblies represent important protease-resting states. However, DegQ is unable to form such 6-mers, suggesting divergent regulatory mechanisms for DegQ and DegP. To understand how the protease activity of DegQ is controlled, we probed its functional properties employing designed protein variants. Combining crystallographic, biochemical, and mutagenic data, we present a mechanistic model that suggests how protease activity of DegQ 12-mers is intrinsically regulated and how deleterious proteolysis by free DegQ 3-mers is prevented. Our study sheds light on a previously uncharacterized component of the prokaryotic stress-response system with implications for other members of the HtrA family.

  • Organizational Affiliation

    Institute of Biochemistry, Center for Structural and Cell Biology in Medicine, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B, C, D
451Legionella falloniiMutation(s): 0 
Find proteins for F8W672 (Legionella fallonii)
Explore F8W672 
Go to UniProtKB:  F8W672
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupF8W672
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.15 Å
  • R-Value Free: 0.251 
  • R-Value Work: 0.211 
  • R-Value Observed: 0.213 
  • Space Group: H 3
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 136.7α = 90
b = 136.7β = 90
c = 327.001γ = 120
Software Package:
Software NamePurpose
SCALAdata scaling
PDB_EXTRACTdata extraction
MOSFLMdata reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2011-06-15
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2023-09-06
    Changes: Data collection, Database references, Refinement description