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Crystal structure of FliG (residues 86-343) from H. pylori
Structural highlights
FunctionFLIG_HELPY One of the proteins that forms a switch complex that is proposed to be located at the base of the basal body. This complex interacts with chemotaxis proteins (such as CheY) in addition to contacting components of the motor that determine the direction of flagellar rotation. Required for flagellum synthesis and motility. In H.pylori four flagellar switch proteins are encoded, FliG, FliM, FliN and FliY.[1] [2] Publication Abstract from PubMedBacterial 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. Multiple conformations of the FliG C-terminal domain provide insight into flagellar motor switching.,Lam KH, Ip WS, Lam YW, Chan SO, Ling TK, Au SW Structure. 2012 Feb 8;20(2):315-25. PMID:22325779[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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