Skip to main content
NCBI home page
The EMBO Journal logoLink to The EMBO Journal
. 1997 Oct 1;16(19):5827–5836. doi: 10.1093/emboj/16.19.5827

Nucleator function of CsgB for the assembly of adhesive surface organelles in Escherichia coli.

Z Bian 1, S Normark 1
PMCID: PMC1170214  PMID: 9312041

Abstract

Curli are surface organelles in Escherichia coli that assemble outside the bacterium through the precipitation of secreted soluble CsgA monomers, requiring the CsgB nucleator protein. Using immunoelectron microscopy and immunoblotting assays, CsgB is shown to be located on the bacterial surface and also as a minor component of wild-type curli. CsgB lacking its 20 N-terminal residues when fused to maltose-binding protein (MBP) can still trigger polymerization of CsgA monomers in vivo. However, the resulting surface organelles are only formed at one of the two bacterial poles and are morphologically distinct from wild-type curli. These Bfco organelles (CsgB-Free Curli-related Organelles) are highly regular structures reacting with anti-CsgA, but not anti-CsgB antibodies. The CsgB of the active MBP-CsgBII fusion is surface exposed but, unlike the native CsgB in wild-type curli, is not detectable in the Bfco organelles. Overexpression of csgB within a csgA mutant results in the formation of short CsgB polymers on the cell surface. It is suggested that in wild-type bacteria, both CsgA and CsgB are secreted proteins. Interaction between CsgA and CsgB triggers wild-type curli formation, resulting in CsgA-CsgB heteropolymers, while surface-anchored CsgB in MBP-CsgBII triggers morphologically distinct, CsgB-free/CsgA Bfco organelles. In the absence of CsgA, CsgB can self-assemble into polymers.

Full Text

The Full Text of this article is available as a PDF (556.3 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Arnqvist A., Olsén A., Normark S. Sigma S-dependent growth-phase induction of the csgBA promoter in Escherichia coli can be achieved in vivo by sigma 70 in the absence of the nucleoid-associated protein H-NS. Mol Microbiol. 1994 Sep;13(6):1021–1032. doi: 10.1111/j.1365-2958.1994.tb00493.x. [DOI] [PubMed] [Google Scholar]
  2. Arnqvist A., Olsén A., Pfeifer J., Russell D. G., Normark S. The Crl protein activates cryptic genes for curli formation and fibronectin binding in Escherichia coli HB101. Mol Microbiol. 1992 Sep;6(17):2443–2452. doi: 10.1111/j.1365-2958.1992.tb01420.x. [DOI] [PubMed] [Google Scholar]
  3. Ben Nasr A., Olsén A., Sjöbring U., Müller-Esterl W., Björck L. Assembly of human contact phase proteins and release of bradykinin at the surface of curli-expressing Escherichia coli. Mol Microbiol. 1996 Jun;20(5):927–935. doi: 10.1111/j.1365-2958.1996.tb02534.x. [DOI] [PubMed] [Google Scholar]
  4. Brinton C. C., Jr The structure, function, synthesis and genetic control of bacterial pili and a molecular model for DNA and RNA transport in gram negative bacteria. Trans N Y Acad Sci. 1965 Jun;27(8):1003–1054. doi: 10.1111/j.2164-0947.1965.tb02342.x. [DOI] [PubMed] [Google Scholar]
  5. Dietzel I., Kolb V., Boos W. Pole cap formation in Escherichia coli following induction of the maltose-binding protein. Arch Microbiol. 1978 Aug 1;118(2):207–218. doi: 10.1007/BF00415731. [DOI] [PubMed] [Google Scholar]
  6. Flock J. I., Hienz S. A., Heimdahl A., Schennings T. Reconsideration of the role of fibronectin binding in endocarditis caused by Staphylococcus aureus. Infect Immun. 1996 May;64(5):1876–1878. doi: 10.1128/iai.64.5.1876-1878.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Hammar M., Arnqvist A., Bian Z., Olsén A., Normark S. Expression of two csg operons is required for production of fibronectin- and congo red-binding curli polymers in Escherichia coli K-12. Mol Microbiol. 1995 Nov;18(4):661–670. doi: 10.1111/j.1365-2958.1995.mmi_18040661.x.. [DOI] [PubMed] [Google Scholar]
  8. Jones C. H., Pinkner J. S., Nicholes A. V., Slonim L. N., Abraham S. N., Hultgren S. J. FimC is a periplasmic PapD-like chaperone that directs assembly of type 1 pili in bacteria. Proc Natl Acad Sci U S A. 1993 Sep 15;90(18):8397–8401. doi: 10.1073/pnas.90.18.8397. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Jones C. H., Pinkner J. S., Roth R., Heuser J., Nicholes A. V., Abraham S. N., Hultgren S. J. FimH adhesin of type 1 pili is assembled into a fibrillar tip structure in the Enterobacteriaceae. Proc Natl Acad Sci U S A. 1995 Mar 14;92(6):2081–2085. doi: 10.1073/pnas.92.6.2081. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Joshi H. C., Palacios M. J., McNamara L., Cleveland D. W. Gamma-tubulin is a centrosomal protein required for cell cycle-dependent microtubule nucleation. Nature. 1992 Mar 5;356(6364):80–83. doi: 10.1038/356080a0. [DOI] [PubMed] [Google Scholar]
  11. Kocks C., Hellio R., Gounon P., Ohayon H., Cossart P. Polarized distribution of Listeria monocytogenes surface protein ActA at the site of directional actin assembly. J Cell Sci. 1993 Jul;105(Pt 3):699–710. doi: 10.1242/jcs.105.3.699. [DOI] [PubMed] [Google Scholar]
  12. Kuehn M. J., Heuser J., Normark S., Hultgren S. J. P pili in uropathogenic E. coli are composite fibres with distinct fibrillar adhesive tips. Nature. 1992 Mar 19;356(6366):252–255. doi: 10.1038/356252a0. [DOI] [PubMed] [Google Scholar]
  13. Lindberg F., Lund B., Johansson L., Normark S. Localization of the receptor-binding protein adhesin at the tip of the bacterial pilus. Nature. 1987 Jul 2;328(6125):84–87. doi: 10.1038/328084a0. [DOI] [PubMed] [Google Scholar]
  14. Ljungh A., Wadström T. Salt aggregation test for measuring cell surface hydrophobicity of urinary Escherichia coli. Eur J Clin Microbiol. 1982 Dec;1(6):388–393. doi: 10.1007/BF02019940. [DOI] [PubMed] [Google Scholar]
  15. Maddock J. R., Shapiro L. Polar location of the chemoreceptor complex in the Escherichia coli cell. Science. 1993 Mar 19;259(5102):1717–1723. doi: 10.1126/science.8456299. [DOI] [PubMed] [Google Scholar]
  16. Olsén A., Arnqvist A., Hammar M., Sukupolvi S., Normark S. The RpoS sigma factor relieves H-NS-mediated transcriptional repression of csgA, the subunit gene of fibronectin-binding curli in Escherichia coli. Mol Microbiol. 1993 Feb;7(4):523–536. doi: 10.1111/j.1365-2958.1993.tb01143.x. [DOI] [PubMed] [Google Scholar]
  17. Olsén A., Jonsson A., Normark S. Fibronectin binding mediated by a novel class of surface organelles on Escherichia coli. Nature. 1989 Apr 20;338(6217):652–655. doi: 10.1038/338652a0. [DOI] [PubMed] [Google Scholar]
  18. Ponniah S., Endres R. O., Hasty D. L., Abraham S. N. Fragmentation of Escherichia coli type 1 fimbriae exposes cryptic D-mannose-binding sites. J Bacteriol. 1991 Jul;173(13):4195–4202. doi: 10.1128/jb.173.13.4195-4202.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Shu H. B., Joshi H. C. Gamma-tubulin can both nucleate microtubule assembly and self-assemble into novel tubular structures in mammalian cells. J Cell Biol. 1995 Sep;130(5):1137–1147. doi: 10.1083/jcb.130.5.1137. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Surgalla M. J., Beesley E. D. Congo red-agar plating medium for detecting pigmentation in Pasteurella pestis. Appl Microbiol. 1969 Nov;18(5):834–837. doi: 10.1128/am.18.5.834-837.1969. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The EMBO Journal are provided here courtesy of Nature Publishing Group

RESOURCES