1UUN

Main porin from Mycobacterium smegmatis (MspA)

• PDB DOI: https://doi.org/10.2210/pdb1UUN/pdb

• Classification: PORIN
• Organism(s): Mycolicibacterium smegmatis
• Expression System: Escherichia coli
• Mutation(s): Yes 
• Membrane Protein: Yes  OPMPDBTMMemProtMDmpstruc


• Deposited: 2004-01-08 Released: 2004-02-26 
• Deposition Author(s): Faller, M., Niederweis, M., Schulz, G.E.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.50 Å
• R-Value Free: 0.249 
• R-Value Work: 0.226 
• R-Value Observed: 0.227 

Literature

The Structure of a Mycobacterial Outer-Membrane Channel

Faller, M., Niederweis, M., Schulz, G.E.

(2004) Science 303: 1189

• PubMed: 14976314 
• DOI: https://doi.org/10.1126/science.1094114
• Primary Citation of Related Structures:  
  1UUN


• PubMed Abstract: 
  

  Mycobacteria have low-permeability outer membranes that render them resistant to most antibiotics. Hydrophilic nutrients can enter by way of transmembrane-channel proteins called porins. An x-ray analysis of the main porin from Mycobacterium smegmatis, MspA, revealed a homooctameric goblet-like conformation with a single central channel. This is the first structure of a mycobacterial outer-membrane protein. No structure-related protein was found in the Protein Data Bank. MspA contains two consecutive beta barrels with nonpolar outer surfaces that form a ribbon around the porin, which is too narrow to fit the thickness of the mycobacterial outer membrane in contemporary models.

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Organizational Affiliation: 

Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Albertstrasse 21, 79104 Freiburg im Breisgau, Germany.

Biological Assembly 1  

Global Symmetry: Cyclic - C8  (Explore in 3D)
Global Stoichiometry: Homo 8-mer - A8 

Biological assembly 1 assigned by authors and generated by PQS (software)

Macromolecule Content

• Total Structure Weight: 39 kDa 
• Atom Count: 2,853 
• Modelled Residue Count: 368 
• Deposited Residue Count: 368 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
MSPA	A, B	184	Mycolicibacterium smegmatis	Mutation(s): 1  Membrane Entity: Yes
UniProt
Find proteins for A0QR29 (Mycolicibacterium smegmatis (strain ATCC 700084 / mc(2)155)) Explore A0QR29  Go to UniProtKB:  A0QR29

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.50 Å
• R-Value Free: 0.249 
• R-Value Work: 0.226 
• R-Value Observed: 0.227 
• Space Group: I 4 2 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 113.86	α = 90
b = 113.86	β = 90
c = 229.3	γ = 90

Software Package:

Software Name	Purpose
REFMAC	refinement
XDS	data reduction
SOLVE	phasing

Structure Validation

Entry History 

Deposition Data

• Released Date: 2004-02-26 
Deposition Author(s): Faller, M., Niederweis, M., Schulz, G.E.

Revision History  

• Version 1.0: 2004-02-26
  Type: Initial release
  
• Version 1.1: 2011-05-08
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2019-07-24
  Changes: Data collection