A structural motif is the recognition site for a new family of bacterial protein O-glycosyltransferases.

Abstract : The Escherichia coli Adhesin Involved in Diffuse Adherence (AIDA-I) is a multifunctional protein that belongs to the family of monomeric autotransporters. This adhesin can be glycosylated by the AIDA-associated heptosyltransferase (Aah). Glycosylation appears to be restricted to the extracellular domain of AIDA-I, which comprises imperfect repeats of a 19-amino-acid consensus sequence and is predicted to form a β-helix. Here, we show that Aah homologues can be found in many Gram-negative bacteria, including Citrobacter rodentium. We demonstrated that an AIDA-like protein is glycosylated in this species by the Aah homologue. We then investigated the substrate recognition mechanism of the E. coli Aah heptosyltransferase. We found that a peptide corresponding to one repeat of the 19-amino-acid consensus is sufficient for recognition and glycosylation by Aah. Mutagenesis studies suggested that, unexpectedly, Aah recognizes a structural motif typical of β-helices, but not a specific sequence. In agreement with this finding, we observed that the extracellular domain of the Bordetella pertussis pertactin, a β-helical polypeptide lacking the 19-amino-acid consensus sequence, could be glycosylated by Aah. Overall, our findings suggest that Aah represents the prototype of a new large family of bacterial protein O-glycosyltransferases that modify various substrates recognized through a structural motif.
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Submitted on : Wednesday, July 25, 2012 - 4:50:08 PM
Last modification on : Wednesday, April 17, 2019 - 12:21:21 PM

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Marie-Ève Charbonneau, Jean-Philippe Côté, M Florencia Haurat, Bela Reiz, Sébastien Crépin, et al.. A structural motif is the recognition site for a new family of bacterial protein O-glycosyltransferases.. Molecular Microbiology, Wiley, 2012, 83 (5), pp.894-907. ⟨10.1111/j.1365-2958.2012.07973.x⟩. ⟨pasteur-00720772⟩

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