Biology:Flagellar motor switch protein

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FliG C-terminal domain
PDB 1lkv EBI.jpg
crystal structure of the middle and c-terminal domains of the flagellar rotor protein flig
Identifiers
SymbolFliG_C
PfamPF01706
Pfam clanCL0436
InterProIPR000090
SCOP21qc7 / SCOPe / SUPFAM
Flagellar motor switch protein FliM
Identifiers
SymbolFliM
PfamPF02154
Pfam clanCL0355
InterProIPR001689

In molecular biology, the flagellar motor switch protein (Flig) is one of three proteins in certain bacteria coded for by the gene fliG.[1] The other two proteins are FliN coded for by fliN,[2] and FliM coded for by fliM.[3] The protein complex regulates the direction of flagellar rotation and hence controls swimming behaviour.[4] The switch is a complex apparatus that responds to signals transduced by the chemotaxis sensory signalling system during chemotactic behaviour.[4] CheY, the chemotaxis response regulator, is believed to act directly on the switch to induce a switch in the flagellar motor direction of rotation.

Fli proteins

The switch complex comprises at least three proteins - FliG, FliM and FliN.[2] It has been shown that FliG interacts with FliM, FliM interacts with itself, and FliM interacts with FliN.[5] Several amino acids within the middle third of FliG appear to be strongly involved in the FliG-FliM interaction, with residues near the N- or C-termini being less important.[5] Such clustering suggests that FliG-FliM interaction plays a central role in switching.

Analysis of the FliG, FliM and FliN sequences shows that none are especially hydrophobic or appear to be integral membrane proteins.[6] This result is consistent with other evidence suggesting that the proteins may be peripheral to the membrane, possibly mounted on the basal body M ring.[6][7] FliG is present in about 25 copies per flagellum. The structure of the C-terminal domain of FliG is known, this domain functions specifically in motor rotation.[8]

References

  1. "flig in UniProtKB". https://www.uniprot.org/uniprot/?query=flig&sort=score. 
  2. 2.0 2.1 "fliN - Flagellar motor switch protein FliN - Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720) - fliN gene & protein". https://www.uniprot.org/uniprot/P26419. 
  3. "flim in UniProtKB". https://www.uniprot.org/uniprot/?query=FliM&sort=score. 
  4. 4.0 4.1 "Gene sequence, overproduction, purification and determination of the wild-type level of the Escherichia coli flagellar switch protein FliG". Gene 133 (1): 103–8. October 1993. doi:10.1016/0378-1119(93)90232-R. PMID 8224881. 
  5. 5.0 5.1 "A mutational analysis of the interaction between FliG and FliM, two components of the flagellar motor of Escherichia coli". J. Bacteriol. 178 (5): 1289–94. March 1996. doi:10.1128/jb.178.5.1289-1294.1996. PMID 8631704. 
  6. 6.0 6.1 "Flagellar switch of Salmonella typhimurium: gene sequences and deduced protein sequences". J. Bacteriol. 171 (6): 3247–57. June 1989. doi:10.1128/jb.171.6.3247-3257.1989. PMID 2656645. 
  7. "Localization of the Salmonella typhimurium flagellar switch protein FliG to the cytoplasmic M-ring face of the basal body". Proc. Natl. Acad. Sci. U.S.A. 89 (14): 6304–8. July 1992. doi:10.1073/pnas.89.14.6304. PMID 1631122. Bibcode1992PNAS...89.6304F. 
  8. "Structure of the C-terminal domain of FliG, a component of the rotor in the bacterial flagellar motor". Nature 400 (6743): 472–5. July 1999. doi:10.1038/22794. PMID 10440379. Bibcode1999Natur.400..472L. 
This article incorporates text from the public domain Pfam and InterPro: IPR001689
This article incorporates text from the public domain Pfam and InterPro: IPR000090