Phage insertion in mlrA and variations in rpoS limit curli expression and biofilm formation in Escherichia coli serotype O157: H7

Gaylen A. Uhlich, Chin Yi Chen, Bryan J. Cottrell, Christopher S. Hofmann, Edward G. Dudley, Terence P. Strobaugh, Ly Huong Nguyen

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Biofilm formation in Escherichia coli is a tightly controlled process requiring the expression of adhesive curli fibres and certain polysaccharides such as cellulose. The transcriptional regulator CsgD is central to biofilm formation, controlling the expression of the curli structural and export proteins and the diguanylate cyclase adrA, which indirectly activates cellulose production. CsgD itself is highly regulated by two sigma factors (RpoS and RpoD), multiple DNA-binding proteins, small regulatory RNAs and several GGDEF/EAL proteins acting through c-di-GMP. One such transcription factor MlrA binds the csgD promoter to enhance the RpoS-dependent transcription of csgD. Bacteriophage, often carrying the stx1 gene, utilize an insertion site in the proximal mlrA coding region of E. coli serotype O157:H7 strains, and the loss of mlrA function would be expected to be the major factor contributing to poor curli and biofilm expression in that serotype. Using a bank of 55 strains of serotype O157: H7, we investigated the consequences of bacteriophage insertion. Although curli/biofilm expression was restored in many of the prophagebearing strains by a wild-type copy of mlrA on a multi-copy plasmid, more than half of the strains showed only partial or no complementation. Moreover, the two strains carrying an intact mlrA were found to be deficient in biofilm formation. However, RpoS mutations that attenuated or inactivated RpoS-dependent functions such as biofilm formation were found in .70% of the strains, including the two strains with an intact mlrA. We conclude that bacteriophage interruption of mlrA and RpoS mutations provide major obstacles limiting curli expression and biofilm formation in most serotype O157:H7 strains.

Original languageEnglish (US)
Pages (from-to)1586-1596
Number of pages11
JournalMicrobiology (United Kingdom)
Volume159
Issue number8
DOIs
StatePublished - Aug 1 2013

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Escherichia coli O157
Biofilms
Bacteriophages
Cellulose
Sigma Factor
Mutation
Insertional Mutagenesis
DNA-Binding Proteins
Serogroup
Adhesives
Polysaccharides
Proteins
Plasmids
Transcription Factors
RNA
Escherichia coli

All Science Journal Classification (ASJC) codes

  • Microbiology

Cite this

Uhlich, Gaylen A. ; Chen, Chin Yi ; Cottrell, Bryan J. ; Hofmann, Christopher S. ; Dudley, Edward G. ; Strobaugh, Terence P. ; Nguyen, Ly Huong. / Phage insertion in mlrA and variations in rpoS limit curli expression and biofilm formation in Escherichia coli serotype O157 : H7. In: Microbiology (United Kingdom). 2013 ; Vol. 159, No. 8. pp. 1586-1596.
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title = "Phage insertion in mlrA and variations in rpoS limit curli expression and biofilm formation in Escherichia coli serotype O157: H7",
abstract = "Biofilm formation in Escherichia coli is a tightly controlled process requiring the expression of adhesive curli fibres and certain polysaccharides such as cellulose. The transcriptional regulator CsgD is central to biofilm formation, controlling the expression of the curli structural and export proteins and the diguanylate cyclase adrA, which indirectly activates cellulose production. CsgD itself is highly regulated by two sigma factors (RpoS and RpoD), multiple DNA-binding proteins, small regulatory RNAs and several GGDEF/EAL proteins acting through c-di-GMP. One such transcription factor MlrA binds the csgD promoter to enhance the RpoS-dependent transcription of csgD. Bacteriophage, often carrying the stx1 gene, utilize an insertion site in the proximal mlrA coding region of E. coli serotype O157:H7 strains, and the loss of mlrA function would be expected to be the major factor contributing to poor curli and biofilm expression in that serotype. Using a bank of 55 strains of serotype O157: H7, we investigated the consequences of bacteriophage insertion. Although curli/biofilm expression was restored in many of the prophagebearing strains by a wild-type copy of mlrA on a multi-copy plasmid, more than half of the strains showed only partial or no complementation. Moreover, the two strains carrying an intact mlrA were found to be deficient in biofilm formation. However, RpoS mutations that attenuated or inactivated RpoS-dependent functions such as biofilm formation were found in .70{\%} of the strains, including the two strains with an intact mlrA. We conclude that bacteriophage interruption of mlrA and RpoS mutations provide major obstacles limiting curli expression and biofilm formation in most serotype O157:H7 strains.",
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Phage insertion in mlrA and variations in rpoS limit curli expression and biofilm formation in Escherichia coli serotype O157 : H7. / Uhlich, Gaylen A.; Chen, Chin Yi; Cottrell, Bryan J.; Hofmann, Christopher S.; Dudley, Edward G.; Strobaugh, Terence P.; Nguyen, Ly Huong.

In: Microbiology (United Kingdom), Vol. 159, No. 8, 01.08.2013, p. 1586-1596.

Research output: Contribution to journalArticle

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T1 - Phage insertion in mlrA and variations in rpoS limit curli expression and biofilm formation in Escherichia coli serotype O157

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AU - Uhlich, Gaylen A.

AU - Chen, Chin Yi

AU - Cottrell, Bryan J.

AU - Hofmann, Christopher S.

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AU - Strobaugh, Terence P.

AU - Nguyen, Ly Huong

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AB - Biofilm formation in Escherichia coli is a tightly controlled process requiring the expression of adhesive curli fibres and certain polysaccharides such as cellulose. The transcriptional regulator CsgD is central to biofilm formation, controlling the expression of the curli structural and export proteins and the diguanylate cyclase adrA, which indirectly activates cellulose production. CsgD itself is highly regulated by two sigma factors (RpoS and RpoD), multiple DNA-binding proteins, small regulatory RNAs and several GGDEF/EAL proteins acting through c-di-GMP. One such transcription factor MlrA binds the csgD promoter to enhance the RpoS-dependent transcription of csgD. Bacteriophage, often carrying the stx1 gene, utilize an insertion site in the proximal mlrA coding region of E. coli serotype O157:H7 strains, and the loss of mlrA function would be expected to be the major factor contributing to poor curli and biofilm expression in that serotype. Using a bank of 55 strains of serotype O157: H7, we investigated the consequences of bacteriophage insertion. Although curli/biofilm expression was restored in many of the prophagebearing strains by a wild-type copy of mlrA on a multi-copy plasmid, more than half of the strains showed only partial or no complementation. Moreover, the two strains carrying an intact mlrA were found to be deficient in biofilm formation. However, RpoS mutations that attenuated or inactivated RpoS-dependent functions such as biofilm formation were found in .70% of the strains, including the two strains with an intact mlrA. We conclude that bacteriophage interruption of mlrA and RpoS mutations provide major obstacles limiting curli expression and biofilm formation in most serotype O157:H7 strains.

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