3USW: Crystal Structure Of Flig (residues 86-343) From H. Pylori

Bacterial flagellar switching between counterclockwise and clockwise directions is mediated by the coupling of the chemotactic system and the motor switch complex. The conformational changes of FliG are closely associated with this switching mechanism. We present two crystal structures of FliG(MC) from Helicobacter pylori, each showing distinct domain orientations from previously solved structures. A 180 degrees rotation of the charged ridge-containing C-terminal subdomain FliG(Calpha1-6) that is prompted by the rotational freedom of Met245 psi and Phe246 phi at the MFXF motif was revealed. Studies on the swarming and swimming behavior of Escherichia coli mutants further identified the importance of the (2)(4)(5)MFXF(2)(4)(8) motif and a highly conserved residue, Asn216, in motor switching. Additionally, multiple conformations of FliG(Calpha1-6) were demonstrated by intramolecular cysteine crosslinking. The conformational flexibility of FliGc leads us to propose a model that accounts for the symmetrical torque generation process and for the dynamics of the motor.
PDB ID: 3USWDownload
MMDB ID: 95789
PDB Deposition Date: 2011/11/24
Updated in MMDB: 2011/12
Experimental Method:
x-ray diffraction
Resolution: 2.6  Å
Source Organism:
Similar Structures:
Biological Unit for 3USW: monomeric; determined by author and by software (PISA)
Molecular Components in 3USW
Label Count Molecule
Protein (1 molecule)
Flagellar Motor Switch Protein(Gene symbol: fliG)
Molecule annotation
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Citing MMDB