The Crl protein activates cryptic genes for curli formation and fibronectin binding in Escherichia coli HB101

Mol Microbiol. 1992 Sep;6(17):2443-52. doi: 10.1111/j.1365-2958.1992.tb01420.x.


Curli are thin, coiled, temperature-regulated fibres on fibronectin-binding Escherichia coli. The subunit protein of curli was highly homologous at its amino terminus to SEF-17, the subunit protein of thin, aggregative fimbriae of Salmonella enteritidis 27655 strain 3b, suggesting that these fibres form a novel class of surface organelles on enterobacteria. E. coli HB101 is non-curliated and unable to bind soluble, iodinated fibronectin. The phenotypically cryptic curlin subunit gene, csgA, in HB101 is transcriptionally activated by expressing the cytoplasmic Crl on a multicopy plasmid. Transcriptional activation of csgA by Crl was observed after growth at 26 degrees C but not at 37 degrees C, even though crl transcription was not thermoregulated. A deletion of the 39 carboxy-terminal residues abolished Crl activity, whereas a deletion of 10 residues at the C-terminus did not, implying that a region between residue 93 and 122 in the 132-amino-acid-residue large Crl protein is required for activating curli expression in E. coli HB101. crl is a normal housekeeping gene in E. coli and it is suggested that its gene product may either be a DNA-binding protein affecting chromatin structure as has been suggested for histone-like protein H1 or interact with specific regulatory protein(s) controlling transcription of genes required for curli formation and fibronectin binding.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Base Sequence
  • Escherichia coli / genetics*
  • Escherichia coli / ultrastructure
  • Escherichia coli Proteins*
  • Fibronectins / metabolism
  • Fimbriae, Bacterial / physiology
  • Gene Expression Regulation, Bacterial / physiology*
  • Genes, Bacterial / physiology*
  • Hot Temperature
  • Molecular Sequence Data
  • Organelles / physiology
  • Transcription, Genetic / physiology


  • Bacterial Proteins
  • Escherichia coli Proteins
  • Fibronectins
  • csgA protein, E coli
  • Crl protein, Bacteria

Associated data

  • GENBANK/627207