This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lowder, B. J. Articles by Blair, D. F. Search for Related Content PubMed PubMed Citation Articles by Lowder, B. J. Articles by Blair, D. F.

FliG Subunit Arrangement in the Flagellar Rotor Probed by Targeted Cross-Linking

Department of Biology, University of Utah, Salt Lake City, Utah 84112

Received 8 April 2005/ Accepted 17 May 2005

FliG is a component of the switch complex on the rotor of the bacterial flagellum. Each flagellar motor contains about 25 FliG molecules. The protein of Escherichia coli has 331 amino acid residues and comprises at least two discrete domains. A C-terminal domain of about 100 residues functions in rotation and includes charged residues that interact with the stator protein MotA. Other parts of the FliG protein are essential for flagellar assembly and interact with the MS ring protein FliF and the switch complex protein FliM. The crystal structure of the middle and C-terminal parts of FliG shows two globular domains joined by an -helix and a short extended segment that contains two well-conserved glycine residues. Here, we describe targeted cross-linking studies of FliG that reveal features of its organization in the flagellum. Cys residues were introduced at various positions, singly or in pairs, and cross-linking by a maleimide or disulfide-inducing oxidant was examined. FliG molecules with pairs of Cys residues at certain positions in the middle domain formed disulfide-linked dimers and larger multimers with a high yield, showing that the middle domains of adjacent subunits are in fairly close proximity and putting constraints on the relative orientation of the domains. Certain proteins with single Cys replacements in the C-terminal domain formed dimers with moderate yields but not larger multimers. On the basis of the cross-linking results and the data available from mutational and electron microscopic studies, we propose a model for the organization of FliG subunits in the flagellum.

This article has been cited by other articles:

• Kojima, S., Furukawa, Y., Matsunami, H., Minamino, T., Namba, K. (2008). Characterization of the Periplasmic Domain of MotB and Implications for Its Role in the Stator Assembly of the Bacterial Flagellar Motor. J. Bacteriol. 190: 3314-3322 [Abstract] [Full Text]  
• Brown, P. N., Terrazas, M., Paul, K., Blair, D. F. (2007). Mutational Analysis of the Flagellar Protein FliG: Sites of Interaction with FliM and Implications for Organization of the Switch Complex. J. Bacteriol. 189: 305-312 [Abstract] [Full Text]  
• Blair, D. F. (2006). Fine structure of a fine machine.. J. Bacteriol. 188: 7033-7035 [Full Text]  
• Thomas, D. R., Francis, N. R., Xu, C., DeRosier, D. J. (2006). The Three-Dimensional Structure of the Flagellar Rotor from a Clockwise-Locked Mutant of Salmonella enterica Serovar Typhimurium.. J. Bacteriol. 188: 7039-7048 [Abstract] [Full Text]  
• Park, S.-Y., Lowder, B., Bilwes, A. M., Blair, D. F., Crane, B. R. (2006). Structure of FliM provides insight into assembly of the switch complex in the bacterial flagella motor. Proc. Natl. Acad. Sci. USA 103: 11886-11891 [Abstract] [Full Text]  
• Paul, K., Blair, D. F. (2006). Organization of FliN Subunits in the Flagellar Motor of Escherichia coli.. J. Bacteriol. 188: 2502-2511 [Abstract] [Full Text]