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A structural motif is the recognition site for a new family of bacterial protein O ‐glycosyltransferases
Author(s) -
Charbonneau MarieÈve,
Côté JeanPhilippe,
Haurat M. Florencia,
Reiz Bela,
Crépin Sébastien,
Berthiaume Frédéric,
Dozois Charles M.,
Feldman Mario F.,
Mourez Michael
Publication year - 2012
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2012.07973.x
Subject(s) - biology , peptide sequence , biochemistry , glycosylation , bacterial adhesin , consensus sequence , sequence motif , escherichia coli , glycosyltransferase , structural motif , sequence alignment , genetics , gene
Summary 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.