Experimental Data Snapshot

  • Resolution: 3.00 Å
  • R-Value Free: 0.312 
  • R-Value Work: 0.241 
  • R-Value Observed: 0.241 

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This is version 1.3 of the entry. See complete history


Crystal structure of colicin Ia.

Wiener, M.Freymann, D.Ghosh, P.Stroud, R.M.

(1997) Nature 385: 461-464

  • DOI: https://doi.org/10.1038/385461a0
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The ion-channel forming colicins A, B, E1, Ia, Ib and N all kill bacterial cells selectively by co-opting bacterial active-transport pathways and forming voltage-gated ion conducting channels across the plasma membrane of the target bacterium. The crystal structure of colicin Ia reveals a molecule 210 A long with three distinct functional domains arranged along a backbone of two extraordinarily long alpha-helices. A central domain at the bend of the hairpin-like structure mediates specific recognition and binding to an outer-membrane receptor. A second domain mediates translocation across the outer membrane via the TonB transport pathway; the TonB-box recognition element of colicin Ia is on one side of three 80 A-long helices arranged as a helical sheet. A third domain is made up of 10 alpha-helices which form a voltage-activated and voltage-gated ion conducting channel across the plasma membrane of the target cell. The two 160 A-long alpha-helices that link the receptor-binding domain to the other domains enable the colicin Ia molecule to span the periplasmic space and contact both the outer and plasma membranes simultaneously during function.

  • Organizational Affiliation

    S-964 Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
COLICIN IA602Escherichia coliMutation(s): 0 
Gene Names: CIA
Find proteins for P06716 (Escherichia coli)
Explore P06716 
Go to UniProtKB:  P06716
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP06716
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.00 Å
  • R-Value Free: 0.312 
  • R-Value Work: 0.241 
  • R-Value Observed: 0.241 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 64.4α = 90
b = 178.6β = 90
c = 285.5γ = 90
Software Package:
Software NamePurpose
X-PLORmodel building
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1998-01-14
    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: 2024-02-07
    Changes: Data collection, Database references