1yab
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(New page: 200px<br /><applet load="1yab" size="450" color="white" frame="true" align="right" spinBox="true" caption="1yab, resolution 3.40Å" /> '''Structure of T. mari...)
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Revision as of 01:42, 25 November 2007
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Structure of T. maritima FliN flagellar rotor protein
Overview
FliN is a component of the bacterial flagellum that is present at levels, of more than 100 copies and forms the bulk of the C ring, a drum-shaped, structure at the inner end of the basal body. FliN interacts with FliG and, FliM to form the rotor-mounted switch complex that controls, clockwise-counterclockwise switching of the motor. In addition to its, functions in motor rotation and switching, FliN is thought to have a role, in the export of proteins that form the exterior structures of the, flagellum (the rod, hook, and filament). Here, we describe the crystal, structure of most of the FliN protein of Thermotoga maritima. FliN is a, tightly intertwined dimer composed mostly of beta sheet. Several, well-conserved hydrophobic residues form a nonpolar patch on the surface, of the molecule. A mutation in the hydrophobic patch affected both, flagellar assembly and switching, showing that this surface feature is, important for FliN function. The association state of FliN in solution was, studied by analytical ultracentrifugation, which provided clues to the, higher-level organization of the protein. T. maritima FliN is primarily a, dimer in solution, and T. maritima FliN and FliM together form a stable, FliM(1)-FliN(4) complex. Escherichia coli FliN forms a stable tetramer in, solution. The arrangement of FliN subunits in the tetramer was modeled by, reference to the crystal structure of tetrameric HrcQB(C), a related, protein that functions in virulence factor secretion in Pseudomonas, syringae. The modeled tetramer is elongated, with approximate dimensions, of 110 by 40 by 35 Angstroms, and it has a large hydrophobic cleft formed, from the hydrophobic patches on the dimers. On the basis of the present, data and available electron microscopic images, we propose a model for the, organization of FliN subunits in the C ring.
About this Structure
1YAB is a Single protein structure of sequence from Thermotoga maritima msb8. Full crystallographic information is available from OCA.
Reference
Crystal structure of the flagellar rotor protein FliN from Thermotoga maritima., Brown PN, Mathews MA, Joss LA, Hill CP, Blair DF, J Bacteriol. 2005 Apr;187(8):2890-902. PMID:15805535
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