title: Antigen-43-mediated autoaggregation impairs motility in Escherichia coli.
abstract: Functional interaction between bacterial surface-displayed autoaggregation proteins such as antigen 43 (Ag43) of Escherichia coli and motility organelles such as flagella has not previously been described. Here, it has been demonstrated for the first time that Ag43-mediated aggregation can inhibit bacterial motility. Ag43 overexpression produces a dominant aggregation phenotype that overrides motility in the presence of low levels of flagella. In contrast, induction of an increased flagellation state prevents Ag43-mediated aggregation. This phenomenon was observed in naturally occurring subpopulations of E. coli as phase variants expressing and not expressing Ag43 revealed contrasting motility phenotypes. The effects were shown to be part of a general mechanism because other short adhesins capable of mediating autoaggregation (AIDA-I and TibA) also impaired motility. These novel insights into the function of bacterial autoaggregation proteins suggest that a balance between these two systems, i.e. autoaggregation and flagellation, influences motility.
authors.affiliation: School of Molecular and Microbial Sciences, University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Glen C
authors.initials: GC
authors.lastname: Ulett
authors.affiliation: Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Richard I
authors.initials: RI
authors.lastname: Webb
authors.affiliation: School of Molecular and Microbial Sciences, University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Schembri
mesh_terms: D018829:Adhesins, Bacterial / Q000502:physiology*; D018830:Adhesins, Escherichia coli / Q000502:physiology; D000942:Antigens, Bacterial / Q000502:physiology*; D001425:Bacterial Outer Membrane Proteins / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000502:physiology; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000502:physiology*; D005407:Flagella / Q000502:physiology; D009068:Movement; D012097:Repressor Proteins / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology
chemical_list: C075559:AIDA-I protein, E coli; D018829:Adhesins, Bacterial; D018830:Adhesins, Escherichia coli; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C118376:antigen 43, E coli; C499299:oxyR protein, E coli