1col
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(New page: 200px<br /><applet load="1col" size="450" color="white" frame="true" align="right" spinBox="true" caption="1col, resolution 2.4Å" /> '''REFINED STRUCTURE OF ...)
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Revision as of 10:30, 20 November 2007
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REFINED STRUCTURE OF THE PORE-FORMING DOMAIN OF COLICIN A AT 2.4 ANGSTROMS RESOLUTION
Overview
The E1 subgroup (E1, A, B, IA, IB, K and N) of anti-bacterial toxins, called colicins is known to form voltage-dependent channels in lipid, bilayers. The crystal structure of the pore-forming domain of colicin A, from Escherichia coli has been refined to the diffraction limit of the, crystals at 2.4 A resolution by means of molecular dynamics and restrained, least-squares methods to a conventional R-factor of 0.18 for all data, between 6.0 and 2.4 A resolution. The polypeptide chain of 204 amino acid, residues consists of ten alpha-helices organized in a three-layer, structure. The helices range in length from 9 to 23 residues with an, average length of 125 residues. The packing arrangement of the helices has, been analysed; the packing is different from that observed in four-helix, bundle proteins. The sites of 83 water molecules have been located and, refined. Analysis of the structure provides insights into the mechanism of, formation of a voltage-gated channel by the protein. Although it is, proposed that substantial tertiary structural changes occur during, membrane insertion, the secondary structural elements remain conserved., This idea has been proposed recently for a number of other, protein-membrane events and thus may have more general applicability.
About this Structure
1COL is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Refined structure of the pore-forming domain of colicin A at 2.4 A resolution., Parker MW, Postma JP, Pattus F, Tucker AD, Tsernoglou D, J Mol Biol. 1992 Apr 5;224(3):639-57. PMID:1373773
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