Crystal structure of MucB

Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.186 
  • R-Value Observed: 0.189 

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Structural basis for the recognition of MucA by MucB and AlgU in Pseudomonas aeruginosa.

Li, S.Lou, X.Xu, Y.Teng, X.Liu, R.Zhang, Q.Wu, W.Wang, Y.Bartlam, M.

(2019) FEBS J 286: 4982-4994

  • DOI: https://doi.org/10.1111/febs.14995
  • Primary Citation of Related Structures:  
    6IN7, 6IN8, 6IN9

  • PubMed Abstract: 

    Alginate production in Pseudomonas aeruginosa is regulated by the alternate σ factor AlgU, which in turn is regulated by the MucABCD system. The anti-σ factor MucA binds AlgU in the cytoplasm and prevents AlgU from binding to the RNA polymerase for transcription. MucB binds MucA in the periplasm and inhibits proteolysis of MucA and subsequent release of AlgU. In this work, we report crystal structures of MucA in complex with AlgU and MucB. A structure of MucB alone reveals the structural changes required for MucA recognition. A unique disulfide bond is identified in MucB, and mutation of this disulfide bond results in a shift from monomer to MucB dimers or tetramers. As MucB tetramers have previously been shown to be unable to bind MucA, this suggests a redox-sensitive stress response mechanism in MucB. The AlgU-MucA structure reveals a conserved σ factor/anti-σ factor complex, but AlgU lacks a disulfide bond conserved in many other σ factors. Our structures reveal the molecular basis for MucA recognition by MucB in the periplasm and AlgU in the cytoplasm, thus providing an important step in understanding the mechanisms that regulate a key signal transduction pathway involved in P. aeruginosa pathogenesis. DATABASE: The atomic coordinates and structure factors for MucA cyto -AlgU, MucB, and MucA peri -MucB have been deposited in the Protein Data Bank (PDB) with the accession code 6IN7, 6IN8, and 6IN9, respectively.

  • Organizational Affiliation

    State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, China.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Sigma factor AlgU regulatory protein MucB299Pseudomonas aeruginosa PAO1Mutation(s): 0 
Gene Names: mucBalgNPA0764
Find proteins for P38108 (Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1))
Explore P38108 
Go to UniProtKB:  P38108
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP38108
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.186 
  • R-Value Observed: 0.189 
  • Space Group: P 65 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 69.076α = 90
b = 69.076β = 90
c = 223.103γ = 120
Software Package:
Software NamePurpose
HKL-3000data reduction
HKL-3000data scaling

Structure Validation

View Full Validation Report

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
National Natural Science Foundation of ChinaChina31570128

Revision History  (Full details and data files)

  • Version 1.0: 2019-07-24
    Type: Initial release
  • Version 1.1: 2020-01-08
    Changes: Database references
  • Version 1.2: 2023-11-22
    Changes: Data collection, Database references, Refinement description