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Cited by 89Escherichia coli research studiesBacterial Genetics and BiotechnologyBiochemical and Structural Characterization

Phase-variable outer membrane proteins in Escherichia coli

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Owen, Peter, Meehan, Mary, de Loughry-Doherty, Helen, Henderson, Ian·1996·FEMS Immunology & Medical Microbiology
DOI 10.1111/j.1574-695x.1996.tb00124.x
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Abstract

Escherichia coli contains at least two phase-variable proteins in its outer membrane. One, termed antigen 43 (Ag43), is the product of the metastable flu gene located at min 43.6 on the E. coli chromosome and is responsible for colony form variation and for autoaggregation in liquid media. Ag43 is composed of two proteinaceous subunits, alpha 43 and beta 43 in 1:1 stoichiometry. alpha 43 (apparent M(r) 60,000) is surface expressed, extends beyond the O-side chains of smooth lipopolysaccharide and is bound to the cell surface through an interaction with beta 43 (apparent M(r) 53,000), itself an integral, heat-modifiable, outer membrane protein. alpha 43 shows limited N-terminal sequence homology with certain enterobacterial adhesins, and notable sequence homology with AIDA-1, an adhesin of diffuse-adhering E. coli. In addition, alpha 43 contains an RGD motif and a consensus sequence for an (autoproteolytic?) aspartyl protease active site. Expression of Ag43 is subject to reversible phase variation-in liquid minimal medium, the rates of variation from Ag43+ to Ag43- states and from Ag43- to Ag43+ states being approximately 2.2 x 10(-3) and approximately 1 x 10(-3), respectively. Phase switching of Ag43 is regulated by DNA methylation (deoxyadenosine methylase (dam) mutants being 'locked OFF') and by OxyR (oxyR mutants being 'locked ON'). It is proposed that OxyR acts as a repressor of Ag43 transcription by binding to unmethylated GATC sites in the regulatory region of the gene. In some strains, Ag43 may also undergo antigenic variation. A 94 kDa immunocrossreactive outer membrane protein, showing similar rates of phase variation, has additionally been detected for some enteropathogenic and uropathogenic strains of E. coli. This 94 kDa protein can be proteolytically cleaved in situ with trypsin to yield two membrane-bound products with M(r)s and properties similar to those of alpha 43 and beta 43. Results suggest that Ag43 may represent one of a family of antigenically-related high-M(r) adhesins which are synthesized as polyprotein precursors. Some members may be processed and presented on the cell surface as bipartite protein complexes (as Ag43). Others can remain uncleaved.

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Crossref · 10.1111/j.1574-695x.1996.tb00124.x

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  • Ag43 is expressed by a high percentage of enteropathogenic (EPEC) and uropathogenic E. coli strains.

    “The flu-encoded autotransporter protein Ag43 is expressed by a high percentage of enteropathogenic (EPEC) and uropathogenic E. coli strains [115] and belongs to the family of autotransporter proteins.”

    From Bacterial autoaggregation (2018) · cites this paper as [115]

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Authors
Owen, P., Meehan, M., de Loughry-Doherty, H., & Henderson, I.
Affiliations
Trinity College Dublin (IE)
ORCID
Henderson, Ian
Venue
FEMS Immunology & Medical Microbiology
Publisher
Oxford University Press (OUP)
Published
1996-12
Volume
16
Issue
2
Pages
63-76
ISSN
  • 0928-8244 (ISSN-L)
  • 1574-695X
DOI
10.1111/j.1574-695x.1996.tb00124.x
OpenAlex
W2046698689
Cited by
88
References
68
Citations by year
2025: 1 · 2024: 4 · 2023: 4 · 2022: 3 · 2021: 1 · 2020: 3 · 2019: 2 · 2018: 1 · 2017: 1 · 2016: 3 · 2015: 3 · 2014: 2 · 2013: 3 · 2012: 1
FWCI
1.99
Type
journal article
Language
en
Open access
Locations
  • FEMS Immunology & Medical Microbiology (publishedVersion)
  • PubMed (publishedVersion)
Funders
Health Research Board
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Endocrinology › Escherichia coli research studies
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Bacterial Genetics and Biotechnology
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Biochemical and Structural Characterization
Keywords
antigen 43, phase variation, Escherichia coli, outer membrane proteins, self-aggregation, DNA methylation, Dam methyltransferase, OxyR, GATC sites, antigenic variation, adhesins, RGD motif, aspartic protease, lipopolysaccharide
MeSH terms
Amino Acid Sequence, Antigenic Variation, Antigens, Bacterial, Antigens, Surface, Bacterial Adhesion, Bacterial Outer Membrane Proteins, Escherichia coli, Molecular Sequence Data

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