Open AccessThe expression and characterization of a putative adhesin B from H. influenzae
Author(s) -
Lu Desheng,
Boyd Beth,
Lingwood Clifford A.
Publication year - 1998
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1998.tb13137.x
Subject(s) - bacterial adhesin , fusion protein , mutant , biology , haemophilus influenzae , recombinant dna , peptide sequence , microbiology and biotechnology , biochemistry , escherichia coli , gene , bacteria , genetics
In the H. influenzae type b (Hib) genome, two putative adhesin B genes, HI0119 and HI0362, have been identified on the basis of homology to the adhesin B (FimA) of Streptococcus parasanguis . We expressed and characterized one of them, HI0119, from a non‐typeable H. influenzae strain (NTHI). This 37 kDa protein was selectively isolated from an H. influenzae surface protein (water) extract by elution from a celite matrix with EDTA. The adhesin B protein is 97.7% identical to that of H. influenzae , strain Rd, has 23.7% identity and 47.8% similarity to FimA of Streptococcus parasanguis but is distinguished from the FimA family by the absence of the N‐terminal lipid anchor consensus sequence LXXC, the presence of a C‐terminal disulfide‐bonded domain, and a central histidine‐rich domain. Recombinant fusion protein bound specifically to celite. Antisera raised against fusion protein recognized a 37 kDa protein from whole cell extracts of H. influenzae on Western blots. A truncated mutant lacking the C‐terminal disulfide‐bonded domain and a Cys 308 to Ser mutant were constructed and expressed as fusion proteins. Both mutants retained celite binding. However, purified fusion proteins could not, unlike H. influenzae , bind Hep2 cells, suggesting that HI0119 may not be an adhesin in this organism.