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| Subject Categories: Membranes & Transport | Structural Biology |
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| The EMBO Journal
(2008) 27, 2171–2180, doi:10.1038/emboj.2008.137 Published online 17 July 2008 |
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| Crystal structures of the OmpF porin: function in a colicin translocon |
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| Eiki Yamashita1, 3, Mariya V Zhalnina1, Stanislav D Zakharov1, 2, Onkar Sharma1 and William A Cramer1 |
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1 Department of Biological Sciences, Purdue University, West Lafayette, IN, USA 2 Institute of Basic Problems of Biology, Russian Academy of Sciences, Puschino, Moscow Region, Russian Federation To whom correspondence should be addressed William A Cramer, Department of Biological Sciences, Purdue University, Lilly Hall of Life Sciences, West Lafayette, Indiana 47907-1392, USA. Tel.: +1 765 494 4956; Fax: +1 765 496 1189; E-mail: waclab@purdue.edu 3 Present address: Institute for Protein Research, Osaka University, Osaka, Japan Received 15 April 2008; Accepted 24 June 2008; Published online 17 July 2008. |
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| Abstract |
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| 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 Å 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 Å 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. |
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| Keywords: colicin E3, intrinsically disordered protein, OmpF porin, receptor BtuB, tol system |
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Top of page MORE ARTICLES LIKE THISThese links to content published by NPG are automatically generated NEWS AND VIEWSPenetrating insights into pore formation Nature Structural Biology News and Views (01 Feb 1997) TolC, a macromolecular periplasmic ?chunnel? Nature Structural Biology News and Views (01 Jul 2000) RESEARCHCrystal structures of the OmpF porin: function in a colicin translocon The EMBO Journal Article Structure of colicin I receptor bound to the R-domain of colicin Ia: implications for protein import The EMBO Journal Article (16 May 2007) |
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