English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Here we report the characterization of anEscherichia coli gene (agn43 ) which encodes the principal phase-variable outer membrane protein termed antigen 43 (Ag43). Theagn43 gene encodes a precursor protein of 107 kDa containing a 52-amino-acid signal sequence. Posttranslational processing generates an α43 subunit (predictedM r of 49,789) and a C-terminal domain (β43 ) with features typical of a bacterial integral outer membrane protein (predictedM r of 51,642). Secondary structure analysis predicts that β43 exists as an 18-stranded β barrel and that Ag43 shows structural organization closely resembling that of immunoglobulin A1 protease type of exoprotein produced by pathogenicNeisseria andHaemophilus spp. The correct processing of the polyprotein to α43 and β43 in OmpT, OmpP, and DegP protease-deficientE. coli strains points to an autocatalytic cleavage mechanism, a hypothesis supported by the occurrence of an aspartyl protease active site within α43 . Ag43, a species-specific antigen, possesses two RGD motifs of the type implicated in binding to human integrins. The mechanism of reversible phase variation was studied by immunochemical analysis of a panel of well-defined regulatory mutants and by analysis of DNA sequences upstream ofagn43 . Evidence strongly suggests that phase variation is regulated by both deoxyadenosine methylase (Dam) and by OxyR. Thus,oxyR mutants are locked on for Ag43 expression, whereasdam mutants are locked off for Ag43 expression. We propose a novel mechanism for the regulation of phase switching in which OxyR competes with Dam for unmethylated GATC sites in the regulatory region of theagn43 gene.

journal of bacteriology

The Major Phase-Variable Outer Membrane Protein of <i>Escherichia coli</i> Structurally Resembles the Immunoglobulin A1 Protease Class of Exported Protein and Is Regulated by a Novel Mechanism Involving Dam and OxyR

The Major Phase-Variable Outer Membrane Protein of Escherichia coli Structurally Resembles the Immunoglobulin A1 Protease Class of Exported Protein and Is Regulated by a Novel Mechanism Involving Dam and OxyR