Logo of jbacterPermissionsJournals.ASM.orgJournalJB ArticleJournal InfoAuthorsReviewers
J Bacteriol. 1996 Mar; 178(5): 1289–1294.
PMCID: PMC177801

A mutational analysis of the interaction between FliG and FliM, two components of the flagellar motor of Escherichia coli.


The motor that drives the flagellar filament of Escherichia coli contains three "switch" proteins (FliG, FliM, and FliN) that together determine the direction of rotation. Each is required, in addition, for flagellar assembly and for torque generation. These proteins interact in the Saccharomyces cerevisiae two-hybrid system: FliG interacts with FliM, FliM interacts with itself, and FliM interacts with FliN. The interaction between FliG and FliM has been subjected to mutational analysis. FliG (fused to the GAL4 DNA-binding domain) and FliM (fused to a GAL4 transcription activation domain) together activate transcription of a GAL4-dependent lacZ reporter gene. DNA encoding FliG was mutagenized by error-prone amplification with Taq polymerase, mutant fliG genes were cloned (as DNA-binding domain-fliG gene fusions) in S. cerevisiae by gap repair of plasmid DNA, and mutants exhibiting an interaction defect were isolated in a two-hybrid screen. The mutations were each mapped to the first, second, or last third of the fliG gene by multifragment cloning in vivo and then identified by DNA sequencing. In this way, we identified 18 interaction-defective and 15 silent (non-interaction-defective) fliG mutations. Several residues within the middle third of FliG are strongly involved in the FliG-FliM interaction, while residues near the N or C terminus are less important. This clustering, when compared with results of previous studies, suggests that the FliG-FliM interaction plays a central role in switching.

Full Text

The Full Text of this article is available as a PDF (247K).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Berg HC. A physicist looks at bacterial chemotaxis. Cold Spring Harb Symp Quant Biol. 1988;53(Pt 1):1–9. [PubMed]
  • Chien CT, Bartel PL, Sternglanz R, Fields S. The two-hybrid system: a method to identify and clone genes for proteins that interact with a protein of interest. Proc Natl Acad Sci U S A. 1991 Nov 1;88(21):9578–9582. [PMC free article] [PubMed]
  • Del Sal G, Manfioletti G, Schneider C. The CTAB-DNA precipitation method: a common mini-scale preparation of template DNA from phagemids, phages or plasmids suitable for sequencing. Biotechniques. 1989 May;7(5):514–520. [PubMed]
  • Fields S, Song O. A novel genetic system to detect protein-protein interactions. Nature. 1989 Jul 20;340(6230):245–246. [PubMed]
  • Francis NR, Sosinsky GE, Thomas D, DeRosier DJ. Isolation, characterization and structure of bacterial flagellar motors containing the switch complex. J Mol Biol. 1994 Jan 28;235(4):1261–1270. [PubMed]
  • Garza AG, Harris-Haller LW, Stoebner RA, Manson MD. Motility protein interactions in the bacterial flagellar motor. Proc Natl Acad Sci U S A. 1995 Mar 14;92(6):1970–1974. [PMC free article] [PubMed]
  • Gill G, Ptashne M. Mutants of GAL4 protein altered in an activation function. Cell. 1987 Oct 9;51(1):121–126. [PubMed]
  • Irikura VM, Kihara M, Yamaguchi S, Sockett H, Macnab RM. Salmonella typhimurium fliG and fliN mutations causing defects in assembly, rotation, and switching of the flagellar motor. J Bacteriol. 1993 Feb;175(3):802–810. [PMC free article] [PubMed]
  • Khan IH, Reese TS, Khan S. The cytoplasmic component of the bacterial flagellar motor. Proc Natl Acad Sci U S A. 1992 Jul 1;89(13):5956–5960. [PMC free article] [PubMed]
  • Kihara M, Homma M, Kutsukake K, Macnab RM. Flagellar switch of Salmonella typhimurium: gene sequences and deduced protein sequences. J Bacteriol. 1989 Jun;171(6):3247–3257. [PMC free article] [PubMed]
  • Magariyama Y, Yamaguchi S, Aizawa S. Genetic and behavioral analysis of flagellar switch mutants of Salmonella typhimurium. J Bacteriol. 1990 Aug;172(8):4359–4369. [PMC free article] [PubMed]
  • Marykwas DL, Passmore SE. Mapping by multifragment cloning in vivo. Proc Natl Acad Sci U S A. 1995 Dec 5;92(25):11701–11705. [PMC free article] [PubMed]
  • Marykwas DL, Schmidt SA, Berg HC. Interacting components of the flagellar motor of Escherichia coli revealed by the two-hybrid system in yeast. J Mol Biol. 1996 Mar 1;256(3):564–576. [PubMed]
  • Muhlrad D, Hunter R, Parker R. A rapid method for localized mutagenesis of yeast genes. Yeast. 1992 Feb;8(2):79–82. [PubMed]
  • Roman SJ, Frantz BB, Matsumura P. Gene sequence, overproduction, purification and determination of the wild-type level of the Escherichia coli flagellar switch protein FliG. Gene. 1993 Oct 29;133(1):103–108. [PubMed]
  • Sockett H, Yamaguchi S, Kihara M, Irikura VM, Macnab RM. Molecular analysis of the flagellar switch protein FliM of Salmonella typhimurium. J Bacteriol. 1992 Feb;174(3):793–806. [PMC free article] [PubMed]
  • Yamaguchi S, Aizawa S, Kihara M, Isomura M, Jones CJ, Macnab RM. Genetic evidence for a switching and energy-transducing complex in the flagellar motor of Salmonella typhimurium. J Bacteriol. 1986 Dec;168(3):1172–1179. [PMC free article] [PubMed]
  • Yamaguchi S, Fujita H, Ishihara A, Aizawa S, Macnab RM. Subdivision of flagellar genes of Salmonella typhimurium into regions responsible for assembly, rotation, and switching. J Bacteriol. 1986 Apr;166(1):187–193. [PMC free article] [PubMed]

Articles from Journal of Bacteriology are provided here courtesy of American Society for Microbiology (ASM)


Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


  • Gene
    Gene links
  • GEO Profiles
    GEO Profiles
    Related GEO records
  • MedGen
    Related information in MedGen
  • Pathways + GO
    Pathways + GO
    Pathways, annotations and biological systems (BioSystems) that cite the current article.
  • Protein
    Published protein sequences
  • PubMed
    PubMed citations for these articles
  • Substance
    PubChem Substance links
  • Taxonomy
    Related taxonomy entry
  • Taxonomy Tree
    Taxonomy Tree

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...