|Gene:||fimA||Accession Numbers: EG10308 (EcoCyc), b4314, ECK4305|
Synonyms: fimD, pilA, pilC
Component of: fimbrial complex (extended summary available)
FimA, the major subunit of the Escherichia coli type 1 fimbriae (pili) has been identified and its gene sequence determined [Orndorff84], [Orndorff85]. A typical pilus is composed of around 1,000 subunits of FimA which form a right-handed helical rod [Russell92a] connected to a short tip fibrillum composed of the adaptor proteins FimG and FimF and the adhesin FimH attached at its distal end [Jones95]. The fimA promoter is contained within fimS, the fim switch, which controls transcription of fimA and the genes for the other fimbrial structural proteins by undergoing a site-specific inversion [Abraham85]
Locations: extracellular space, pilus
|Map Position: [4,541,138 -> 4,541,686] (97.88 centisomes, 352°)||Length: 549 bp / 182 aa|
Molecular Weight of Polypeptide: 18.111 kD (from nucleotide sequence), 16.5 kD (experimental) [Klemm85 ]
Unification Links: ASAP:ABE-0014145 , CGSC:18358 , DIP:DIP-9609N , EchoBASE:EB0304 , EcoGene:EG10308 , EcoliWiki:b4314 , ModBase:P04128 , OU-Microarray:b4314 , PortEco:fimA , PR:PRO_000022616 , Pride:P04128 , Protein Model Portal:P04128 , RefSeq:NP_418734 , RegulonDB:EG10308 , SMR:P04128 , String:511145.b4314 , UniProt:P04128
In Paralogous Gene Group: 43 (37 members)
|Biological Process:||GO:0007155 - cell adhesion [GOA01a, Klemm85]|
|Cellular Component:||GO:0005576 - extracellular region
GO:0009289 - pilus [UniProtGOA11a, UniProtGOA11, GOA01a, Klemm84]
|MultiFun Terms:||cell structure → pilus|
|Growth Medium||Growth?||T (°C)||O2||pH||Osm/L||Growth Observations|
|LB Lennox||Yes||37||Aerobic||7||Yes [Baba06, Comment 1]|
|M9 medium with 1% glycerol||Yes||37||Aerobic||7.2||0.35||Yes [Joyce06, Comment 2]|
|MOPS medium with 0.4% glucose||Yes||37||Aerobic||7.2||0.22||Yes [Baba06, Comment 1]|
Subunit of: fimbrial complex
Synonyms: type 1 pilin complex
Subunit composition of
fimbrial complex = [FimA][FimF][FimG][FimH]
major type 1 subunit fimbrin (pilin) = FimA (summary available)
fimbrial morphology = FimF (summary available)
fimbrial morphology = FimG (summary available)
minor fimbrial subunit, D-mannose specific adhesin = FimH (extended summary available)
Type 1, or mannose-sensitive, pili, or fimbriae, are found on most Escherichia coli strains [Hahn02]. A fimbriated bacterium typically has 200 to 500 fimbriae peritrichously arranged on its surface. Each fimbria is 7 nm in width and 1 um in length, rod-shaped and comprised of four different protein subunit components that are added to the base of the growing organelle [Lowe87].
The predominant subunit is FimA, which is present in up to 3,000 copies and polymerizes into a right-handed helix that is joined to a thin linear tip fibrillum by smaller numbers of adaptor proteins, FimF and FimG [Russell92a], [Krogfelt88]. Binding to mannose is mediated by FimH adhesin, which is located at the tip of the fimbria as well as laterally in the fimbrial structure [Jones95], [Krogfelt90]. In addition to the structural pilus subunits FimA, FimF, FimG and FimH, two additional proteins whose genes also lie within the type 1 pilus gene cluster are required for the biogenesis of type 1 pili. FimD is the assembly platform which anchores the pilus to the bacterial surface and mediates pilus subunit translocation across the outer membrane [Klemm90]. FimC is the chaperone which complexes with the individual fimbrial subunits to deliver them to the FimD assembly platform [Klemm92]. The FimC /FimD assembly mechanism is referred to as the chaperone-usher pathway [Vetsch02]. A model for the pathway mechanism, based on single particle cryo-electron microscopy images obtained of FimD bound to a pilus translocation intermediate [Remaut08], has been proposed [Daniels08].
Translocation across the inner membrane of the structural and assembly components for type 1 pili occurs through the Sec general secretory pathway across the inner membrane into the periplasm [Mori01].
The expression of genes for type 1 fimbriae is subject to a mode of regulatory control known as phase variation [Gally96]. In phase variation, individual cells switch between a state of expression (fimbriate) and non-expression (afimbriate) and thereby produce a population of mixed cell types. Phase variation of type 1 fimbriae in Escherichia coli is influenced by the orientation of the fim switch, fimS, a 314 bp invertible DNA element [Abraham85]. Recombination of the fim switch requires the fimB and fimE gene products, considered to be the fim recombinases [Gally96]. Mutation deletion analyses of fimB and fimE mutants indicates that fimB is able to mediate recombination in both directions (on-to-off and off-to-on) while fimE only stimulates recombination in the on-to-off direction [McClain93a]. Inversions of the fim switch at normal frequencies also requires the expression of himA and himD, which are the genes for the two subunits of integration host factor (IHF) [Dorman87], lrp, the leucine-responsive regulatory protein [Gally94] and hns, the histone-like protein H1 [Kawula91]. The fim switch in E.coli K-12 is regulated by environmental conditions such as temperature and culture media. Switching can occur rapidly and fimbriae can be lost from the surface within a few generations. The synthesis of type 1 pili is likely repressed at temperatures outside those of mammalian hosts [Gally93]. Exponential growth in in well aerated conditions and growth on agar favour afimbriate cells whereas growth in static broth or under anaerobic conditions favours the isolation of fimbriate cells [Gally93].
Fim phase variation has been monitored in E. coli using a GFPmut2 (green fluorescent protein) reporter gene inserted into fimA - the first gene of the fim operon. These studies have shown a correlation between cell cycle dynamics and fim switching behaviour [Adiciptaningrum09].
The pathway for the biogenesis of type 1 pili - the chaperone-usher pathway - and the structure of the individual pilus subunits has been extensively characterised in uropathogenic E. coli (reviews: [Hultgren91, Waksman09, Geibel11, Busch12, Allen12].
|Biological Process:||GO:0007155 - cell adhesion [Klemm85]|
|Cellular Component:||GO:0009289 - pilus [Gally93]|
|Signal-Sequence||1 -> 23|
|Chain||24 -> 182|
10/20/97 Gene b4314 from Blattner lab Genbank (v. M52) entry merged into EcoCyc gene EG10308; confirmed by SwissProt match.
Abraham85: Abraham JM, Freitag CS, Clements JR, Eisenstein BI (1985). "An invertible element of DNA controls phase variation of type 1 fimbriae of Escherichia coli." Proc Natl Acad Sci U S A 82(17);5724-7. PMID: 2863818
Baba06: Baba T, Ara T, Hasegawa M, Takai Y, Okumura Y, Baba M, Datsenko KA, Tomita M, Wanner BL, Mori H (2006). "Construction of Escherichia coli K-12 in-frame, single-gene knockout mutants: the Keio collection." Mol Syst Biol 2;2006.0008. PMID: 16738554
DiazMejia09: Diaz-Mejia JJ, Babu M, Emili A (2009). "Computational and experimental approaches to chart the Escherichia coli cell-envelope-associated proteome and interactome." FEMS Microbiol Rev 33(1);66-97. PMID: 19054114
Dorman87: Dorman CJ, Higgins CF (1987). "Fimbrial phase variation in Escherichia coli: dependence on integration host factor and homologies with other site-specific recombinases." J Bacteriol 169(8);3840-3. PMID: 2886490
Gally93: Gally DL, Bogan JA, Eisenstein BI, Blomfield IC (1993). "Environmental regulation of the fim switch controlling type 1 fimbrial phase variation in Escherichia coli K-12: effects of temperature and media." J Bacteriol 175(19);6186-93. PMID: 8104927
Gally94: Gally DL, Rucker TJ, Blomfield IC (1994). "The leucine-responsive regulatory protein binds to the fim switch to control phase variation of type 1 fimbrial expression in Escherichia coli K-12." J Bacteriol 1994;176(18);5665-72. PMID: 7916011
Gally96: Gally DL, Leathart J, Blomfield IC (1996). "Interaction of FimB and FimE with the fim switch that controls the phase variation of type 1 fimbriae in Escherichia coli K-12." Mol Microbiol 21(4);725-38. PMID: 8878036
Hahn02: Hahn E, Wild P, Hermanns U, Sebbel P, Glockshuber R, Haner M, Taschner N, Burkhard P, Aebi U, Muller SA (2002). "Exploring the 3D molecular architecture of Escherichia coli type 1 pili." J Mol Biol 323(5);845-57. PMID: 12417198
Jones95: Jones CH, Pinkner JS, Roth R, Heuser J, Nicholes AV, Abraham SN, Hultgren SJ (1995). "FimH adhesin of type 1 pili is assembled into a fibrillar tip structure in the Enterobacteriaceae." Proc Natl Acad Sci U S A 92(6);2081-5. PMID: 7892228
Joyce06: Joyce AR, Reed JL, White A, Edwards R, Osterman A, Baba T, Mori H, Lesely SA, Palsson BO, Agarwalla S (2006). "Experimental and computational assessment of conditionally essential genes in Escherichia coli." J Bacteriol 188(23);8259-71. PMID: 17012394
Klemm85: Klemm P, Jorgensen BJ, van Die I, de Ree H, Bergmans H (1985). "The fim genes responsible for synthesis of type 1 fimbriae in Escherichia coli, cloning and genetic organization." Mol Gen Genet 199(3);410-4. PMID: 2863734
Krogfelt90: Krogfelt KA, Bergmans H, Klemm P (1990). "Direct evidence that the FimH protein is the mannose-specific adhesin of Escherichia coli type 1 fimbriae." Infect Immun 58(6);1995-8. PMID: 1971261
Remaut08: Remaut H, Tang C, Henderson NS, Pinkner JS, Wang T, Hultgren SJ, Thanassi DG, Waksman G, Li H (2008). "Fiber formation across the bacterial outer membrane by the chaperone/usher pathway." Cell 133(4);640-52. PMID: 18485872
Russell92a: Russell PW, Orndorff PE (1992). "Lesions in two Escherichia coli type 1 pilus genes alter pilus number and length without affecting receptor binding." J Bacteriol 174(18);5923-35. PMID: 1355769
Blomfield97: Blomfield IC, Kulasekara DH, Eisenstein BI (1997). "Integration host factor stimulates both FimB- and FimE-mediated site-specific DNA inversion that controls phase variation of type 1 fimbriae expression in Escherichia coli." Mol Microbiol 23(4);705-17. PMID: 9157242
Blumer05: Blumer C, Kleefeld A, Lehnen D, Heintz M, Dobrindt U, Nagy G, Michaelis K, Emody L, Polen T, Rachel R, Wendisch VF, Unden G (2005). "Regulation of type 1 fimbriae synthesis and biofilm formation by the transcriptional regulator LrhA of Escherichia coli." Microbiology 151(Pt 10);3287-98. PMID: 16207912
Dove96: Dove SL, Dorman CJ (1996). "Multicopy fimB gene expression in Escherichia coli: binding to inverted repeats in vivo, effect on fimA gene transcription and DNA inversion." Mol Microbiol 21(6);1161-73. PMID: 8898385
Kulasekara99: Kulasekara HD, Blomfield IC (1999). "The molecular basis for the specificity of fimE in the phase variation of type 1 fimbriae of Escherichia coli K-12." Mol Microbiol 31(4);1171-81. PMID: 10096084
Olsen94a: Olsen PB, Klemm P (1994). "Localization of promoters in the fim gene cluster and the effect of H-NS on the transcription of fimB and fimE." FEMS Microbiol Lett 1994;116(1);95-100. PMID: 7510658
Roesch98: Roesch PL, Blomfield IC (1998). "Leucine alters the interaction of the leucine-responsive regulatory protein (Lrp) with the fim switch to stimulate site-specific recombination in Escherichia coli." Mol Microbiol 1998;27(4);751-61. PMID: 9515701
Schembri98: Schembri MA, Olsen PB, Klemm P (1998). "Orientation-dependent enhancement by H-NS of the activity of the type 1 fimbrial phase switch promoter in Escherichia coli." Mol Gen Genet 1998;259(3);336-44. PMID: 9749677
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