Structure-function analysis of the self-recognizing Antigen 43 autotransporter protein from Escherichia coli

Klemm, P., Hjerrild, L., Gjermansen, M. and Schembri, M. A. (2004) Structure-function analysis of the self-recognizing Antigen 43 autotransporter protein from Escherichia coli. Molecular Microbiology, 51 1: 283-296. doi:10.1046/j.1365-2958.2003.03833.x


Author Klemm, P.
Hjerrild, L.
Gjermansen, M.
Schembri, M. A.
Title Structure-function analysis of the self-recognizing Antigen 43 autotransporter protein from Escherichia coli
Journal name Molecular Microbiology   Check publisher's open access policy
ISSN 0950-382X
Publication date 2004-01-01
Sub-type Article (original research)
DOI 10.1046/j.1365-2958.2003.03833.x
Volume 51
Issue 1
Start page 283
End page 296
Total pages 14
Place of publication Oxford
Publisher Blackwell Publishing Ltd
Language eng
Subject 320401 Medical Bacteriology
270306 Microbial Genetics
270307 Microbial Ecology
Abstract Antigen 43 (Ag43) is a self-recognizing surface adhesin found in most Escherichia coli strains. Expression of Ag43 confers aggregation and fluffing of cells, promotes biofilm formation and is associated with enhanced resistance to antimicrobial agents. Ag43 is an autotransporter protein and consists of two moieties: a transporter, the beta-module, and a passenger domain, the alpha-module. Here we have employed various molecular approaches to probe structure/function aspects of Ag43. An entire family of Ag43 variants was identified. The gene encoding Ag43 (flu) was cloned from a diverse range of E. coli subtypes and found to encode variant proteins with different properties. Several novel variants were identified and characterized that were unable to promote cell-cell aggregation. By employing a combination of linker insertion mutagenesis and domain swapping between clumping and non-clumping variants, we have pinpointed the region of the protein responsible for autoaggregation to be located within the N-terminal one-third of the passenger domain. Our data suggest that ionic interactions between charged residues residing in interacting pairs of Ag43(alpha) domains may be important for the self-recognition process. Based on its similarity to other related proteins, we predict the passenger, Ag43(alpha), domain primarily to consist of an extended beta-helix structure in which numerous repeats or rungs are stacked in parallel orientation in an extended cylindrical formation. Finally, we found that in spite of their different aggregative pattern all Ag43 variants promoted biofilm formation to abiotic surfaces.
Keyword Biochemistry & Molecular Biology
Microbiology
Outer-membrane Protein
Bordetella-pertussis
Colony Morphology
Aggregative Adherence
Type-1 Fimbriae
Gene-expression
Phase Variation
Hep-2 Cells
Virulence
Autoaggregation
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: Excellence in Research Australia (ERA) - Collection
School of Chemistry and Molecular Biosciences
 
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