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N‐terminal characterization of the Bordetella pertussis filamentous haemagglutinin
Author(s) -
LambertBuisine Corinne,
Willery Eve,
Locht Camille,
JacobDubuisson Françoise
Publication year - 1998
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 - 10.1046/j.1365-2958.1998.00892.x
Subject(s) - signal peptide , biology , bordetella pertussis , signal peptidase , secretion , biochemistry , escherichia coli , site directed mutagenesis , bordetella , peptide sequence , bacterial adhesin , secretory protein , microbiology and biotechnology , bacteria , mutant , genetics , gene
The major adhesin of Bordetella pertussis , filamentous haemagglutinin (FHA), is produced and secreted at high levels by the bacterium. Mature FHA derives from a large precursor, FhaB, that undergoes several post‐translational maturations. In this work, we demonstrate by site‐directed mutagenesis that the N‐terminal signal peptide of FHA is composed of 71 amino acids, including a 22‐residue‐long ‘N‐terminal extension’ sequence. This sequence, although highly conserved in various other secretory proteins, does not appear to play an essential part in FHA secretion, as shown by deletion mutagenesis. The entire N‐terminal signal region of FhaB is removed in the course of secretion by proteolytic cleavage at a site that corresponds to a Lep signal peptidase recognition sequence. After this maturation, the N‐terminal glutamine residue is modified to a pyroglutamate residue. This modification is not crucial for heparin binding, haemagglutination or secretion. Interestingly, however, the modification is absent from Escherichia coli secreted FHA derivatives. In addition, it is dependent in B. pertussis on the presence of all three cysteines contained in the signal peptide of FhaB. These observations suggest that it does not occur spontaneously but perhaps requires a specific enzymatic machinery.