4Z7X

MdbA protein, a thiol-disulfide oxidoreductase from Actinomyces oris.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.55 Å
  • R-Value Free: 0.180 
  • R-Value Work: 0.124 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

A Disulfide Bond-forming Machine Is Linked to the Sortase-mediated Pilus Assembly Pathway in the Gram-positive Bacterium Actinomyces oris.

Reardon-Robinson, M.E.Osipiuk, J.Chang, C.Wu, C.Jooya, N.Joachimiak, A.Das, A.Ton-That, H.

(2015) J.Biol.Chem. 290: 21393-21405

  • DOI: 10.1074/jbc.M115.672253

  • PubMed Abstract: 
  • Export of cell surface pilins in Gram-positive bacteria likely occurs by the translocation of unfolded precursor polypeptides; however, how the unfolded pilins gain their native conformation is presently unknown. Here, we present physiological studie ...

    Export of cell surface pilins in Gram-positive bacteria likely occurs by the translocation of unfolded precursor polypeptides; however, how the unfolded pilins gain their native conformation is presently unknown. Here, we present physiological studies to demonstrate that the FimA pilin of Actinomyces oris contains two disulfide bonds. Alanine substitution of cysteine residues forming the C-terminal disulfide bridge abrogates pilus assembly, in turn eliminating biofilm formation and polymicrobial interaction. Transposon mutagenesis of A. oris yielded a mutant defective in adherence to Streptococcus oralis, and revealed the essential role of a vitamin K epoxide reductase (VKOR) gene in pilus assembly. Targeted deletion of vkor results in the same defects, which are rescued by ectopic expression of VKOR, but not a mutant containing an alanine substitution in its conserved CXXC motif. Depletion of mdbA, which encodes a membrane-bound thiol-disulfide oxidoreductase, abrogates pilus assembly and alters cell morphology. Remarkably, overexpression of MdbA or a counterpart from Corynebacterium diphtheriae, rescues the Δvkor mutant. By alkylation assays, we demonstrate that VKOR is required for MdbA reoxidation. Furthermore, crystallographic studies reveal that A. oris MdbA harbors a thioredoxin-like fold with the conserved CXXC active site. Consistently, each MdbA enzyme catalyzes proper disulfide bond formation within FimA in vitro that requires the catalytic CXXC motif. Because the majority of signal peptide-containing proteins encoded by A. oris possess multiple Cys residues, we propose that MdbA and VKOR constitute a major folding machine for the secretome of this organism. This oxidative protein folding pathway may be a common feature in Actinobacteria.


    Organizational Affiliation

    From the Department of Microbiology and Molecular Genetics, University of Texas Health Science Center, Houston, Texas 77030.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
MdbA
A, B
238Actinomyces orisMutation(s): 0 
Gene Names: mdbA
Find proteins for A0A0M3KL32 (Actinomyces oris)
Go to UniProtKB:  A0A0M3KL32
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
3CX
Query on 3CX

Download SDF File 
Download CCD File 
A, B
(2S)-3-(cyclohexylamino)-2-hydroxypropane-1-sulfonic acid
C9 H19 N O4 S
INEWUCPYEUEQTN-VIFPVBQESA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
MSE
Query on MSE
A, B
L-PEPTIDE LINKINGC5 H11 N O2 SeMET
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.55 Å
  • R-Value Free: 0.180 
  • R-Value Work: 0.124 
  • Space Group: C 2 2 21
Unit Cell:
Length (Å)Angle (°)
a = 46.880α = 90.00
b = 66.860β = 90.00
c = 256.169γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement
HKL-3000phasing
HKL-3000data scaling
PDB_EXTRACTdata extraction
HKL-3000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of General Medical SciencesUnited StatesGM094585
National Institutes of Health/National Institute of Dental and Craniofacial ResearchUnited StatesDE017382
National Institutes of Health/National Institute of Dental and Craniofacial ResearchUnited StatesDE025015

Revision History 

  • Version 1.0: 2015-04-22
    Type: Initial release
  • Version 1.1: 2015-09-09
    Type: Database references
  • Version 1.2: 2017-09-20
    Type: Author supporting evidence, Database references, Derived calculations