Glycosylation with heptose residues mediated by the aah gene product is essential for adherence of the AIDA-I adhesin.

Abstract

The diffuse adherence of Escherichia coli strain 2787 (O126:H27) is mediated by the autotransporter adhesin AIDA-I (adhesin-involved-in-diffuse-adherence) encoded by the plasmid-borne aidA gene. AIDA-I exhibits an aberrant mobility in denaturing gel electrophoresis. Deletion of the open reading frame (ORF) A immediately upstream of aidA restores the predicted mobility of AIDA-I, but the adhesin is no longer functional. This indicates that the mature AIDA-I adhesin is post-translationally modified and the modification is essential for adherence function. Labelling with digoxigenin hydrazide shows AIDA-I to be glycosylated. Using carbohydrate composition analysis, AIDA-I contains exclusively heptose residues (ratio heptose:AIDA-I approximately 19:1). The deduced amino acid sequence of the cytoplasmic open reading frame (ORF) A gene product shows homologies to heptosyltransferases. In addition, the modification was completely abolished in an ADP-glycero-manno-heptopyranose mutant. Our results provide direct evidence for glycosylation of the AIDA-I adhesin by heptoses with the ORF A gene product as a specific (mono)heptosyltransferase generating the functional mature AIDA-I adhesin. Consequently, the ORF A gene has been denoted 'aah' (autotransporter-adhesin-heptosyltransferase). Glycosylation by heptoses represents a novel protein modification in eubacteria.

• Authors: I Benz, M A Schmidt
• Journal: Molecular microbiology (Mol Microbiol) Vol. 40 Issue 6 Pg. 1403-13 (Jun 2001) ISSN: 0950-382X [Print] England
• PMID: 11442838 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• AIDA-I protein, E coli
• Adhesins, Escherichia coli
• Carbohydrates
• Escherichia coli Proteins
• Heptoses
• Glycosyltransferases
• autotransporter-adhesin-heptosyltransferase, E coli

Topics

• Adhesins, Escherichia coli (genetics, immunology, metabolism)
• Amino Acid Sequence
• Bacterial Adhesion (physiology)
• Carbohydrates (analysis)
• Escherichia coli (physiology)
• Escherichia coli Proteins
• Gene Order
• Glycosylation
• Glycosyltransferases (genetics, metabolism)
• HeLa Cells (microbiology)
• Heptoses (metabolism)
• Humans
• Molecular Sequence Data
• Open Reading Frames
• Plasmids
• Protein Processing, Post-Translational
• Sequence Homology, Amino Acid