1OSM

OSMOPORIN (OMPK36) FROM KLEBSIELLA PNEUMONIAE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.20 Å
  • R-Value Free: 0.223 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.208 

Starting Model: experimental
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This is version 1.5 of the entry. See complete history


Literature

Crystal structure and functional characterization of OmpK36, the osmoporin of Klebsiella pneumoniae.

Dutzler, R.Rummel, G.Alberti, S.Hernandez-Alles, S.Phale, P.Rosenbusch, J.Benedi, V.Schirmer, T.

(1999) Structure 7: 425-434

  • DOI: https://doi.org/10.1016/s0969-2126(99)80055-0
  • Primary Citation of Related Structures:  
    1OSM

  • PubMed Abstract: 

    Porins are channel-forming membrane proteins that confer solute permeability to the outer membrane of Gram-negative bacteria. In Escherichia coli, major nonspecific porins are matrix porin (OmpF) and osmoporin (OmpC), which show high sequence homology. In response to high osmolarity of the medium, OmpC is expressed at the expense of OmpF porin. Here, we study osmoporin of the pathogenic Klebsiella pneumoniae (OmpK36), which shares 87% sequence identity with E. coliOmpC in an attempt to establish why osmoporin is best suited to function at high osmotic pressure. The crystal structure of OmpK36 has been determined to a resolution of 3.2 A by molecular replacement with the model of OmpF. The structure of OmpK36 closely resembles that of the search model. The homotrimeric structure is composed of three hollow 16-stranded antiparallel beta barrels, each delimiting a separate pore. Most insertions and deletions with respect to OmpF are found in the loops that protrude towards the cell exterior. A characteristic ten-residue insertion in loop 4 contributes to the subunit interface. At the pore constriction, the replacement of an alanine by a tyrosine residue does not alter the pore profile of OmpK36 in comparison with OmpF because of the different course of the mainchain. Functionally, as characterized in lipid bilayers and liposomes, OmpK36 resembles OmpC with decreased conductance and increased cation selectivity in comparison with OmpF. The osmoporin structure suggests that not an altered pore size but an increase in charge density is the basis for the distinct physico-chemical properties of this porin that are relevant for its preferential expression at high osmotic strength.


  • Organizational Affiliation

    Department of Structural Biology, Biozentrum University of Basel, CH-4056 Basel, Switzerland.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
OMPK36
A, B, C
342Klebsiella pneumoniaeMutation(s): 0 
Membrane Entity: Yes 
UniProt
Find proteins for Q48473 (Klebsiella pneumoniae)
Explore Q48473 
Go to UniProtKB:  Q48473
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ48473
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.20 Å
  • R-Value Free: 0.223 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.208 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 191.8α = 90
b = 76.8β = 113.3
c = 223.4γ = 90
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
MOSFLMdata reduction
CCP4data scaling
ROTAVATAdata scaling
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1999-07-26
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2011-11-30
    Changes: Other
  • Version 1.4: 2023-08-09
    Changes: Database references, Derived calculations, Other, Refinement description
  • Version 1.5: 2024-05-22
    Changes: Data collection