PMID:19858188
| Citation |
Sarkar, MK, Paul, K and Blair, DF (2010) Subunit organization and reversal-associated movements in the flagellar switch of Escherichia coli. J. Biol. Chem. 285:675-84 |
|---|---|
| Abstract |
Bacterial flagella contain a rotor-mounted protein complex termed the switch complex that functions in flagellar assembly, rotation, and clockwise/counterclockwise direction control. In Escherichia coli and Salmonella, the switch complex contains the proteins FliG, FliM, and FliN and corresponds structurally with the C-ring in the flagellar basal body. Certain features of subunit organization in the switch complex have been deduced previously, but details of subunit organization in the lower part of the C-ring and the molecular movements responsible for motor switching remain unclear. In this study, we use cross-linking, binding, and mutational experiments to examine subunit organization in the bottom of the C-ring and to probe movements that occur upon switching. The results show that FliN tetramers alternate with FliM C-terminal domains to form the bottom of the C-ring in an arrangement that closely reproduces the major features observed in electron microscopic reconstructions. When motors were switched to clockwise rotation by a repellent stimulus, cross-link yields were altered in a pattern indicating relative movement of FliN and FliM(C). These results are discussed in the framework of a structurally grounded hypothesis for the switching mechanism. |
| Links |
PubMed PMC2804215 Online version:10.1074/jbc.M109.068676 |
| Keywords |
Amino Acid Sequence; Bacterial Proteins/chemistry; Bacterial Proteins/metabolism; Cross-Linking Reagents/pharmacology; Cysteine/metabolism; DNA Mutational Analysis; Disulfides/metabolism; Escherichia coli/drug effects; Escherichia coli/metabolism; Flagella/drug effects; Flagella/metabolism; Models, Molecular; Molecular Sequence Data; Movement/drug effects; Phenotype; Protein Binding/drug effects; Protein Structure, Secondary; Protein Subunits/chemistry; Protein Subunits/metabolism; Rotation; Structural Homology, Protein; Surface Properties/drug effects |
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