2ZFG: Structure Of Ompf Porin

The OmpF porin in the Escherichia coli outer membrane (OM) is required for the cytotoxic action of group A colicins, which are proposed to insert their translocation and active domains through OmpF pores. A crystal structure was sought of OmpF with an inserted colicin segment. A 1.6 A OmpF structure, obtained from crystals formed in 1 M Mg2+, has one Mg2+ bound in the selectivity filter between Asp113 and Glu117 of loop 3. Co-crystallization of OmpF with the unfolded 83 residue glycine-rich N-terminal segment of colicin E3 (T83) that occludes OmpF ion channels yielded a 3.0 A structure with inserted T83, which was obtained without Mg2+ as was T83 binding to OmpF. The incremental electron density could be modelled as an extended poly-glycine peptide of at least seven residues. It overlapped the Mg2+ binding site obtained without T83, explaining the absence of peptide binding in the presence of Mg2+. Involvement of OmpF in colicin passage through the OM was further documented by immuno-extraction of an OM complex, the colicin translocon, consisting of colicin E3, BtuB and OmpF.
PDB ID: 2ZFGDownload
MMDB ID: 65716
PDB Deposition Date: 2008/1/4
Updated in MMDB: 2012/10
Experimental Method:
x-ray diffraction
Resolution: 1.59  Å
Source Organism:
Similar Structures:
Biological Unit for 2ZFG: trimeric; determined by author and by software (PISA)
Molecular Components in 2ZFG
Label Count Molecule
Proteins (3 molecules)
Outer Membrane Protein F(Gene symbol: ompF)
Molecule annotation
Chemicals (6 molecules)
* Click molecule labels to explore molecular sequence information.

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