Cloning and expression of an adhesin antigen of Streptococcus sanguis G9B in Escherichia coli

Rosan, B.; Baker, C.T.; Nelson, G.M.; Berman, R.; Lamont, R.J.; Demuth, D.R.

Journal of General Microbiology 135(3): 531-538


ISSN/ISBN: 0022-1287
PMID: 2695596
DOI: 10.1099/00221287-135-3-531
Accession: 007125069

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A genomic library of Streptococcus sanguis, strain G9B, was constructed and expressed in Escherichia coli using a .lambda.gt11 expression vector. The amplified library was probed with polyclonal anti-G9B IgG and 13 antigen-positive clones were isolated. A lysate of one clone, designated PP39, absorbed the adhesion-inhibitory activity of anti-G9B IgG. This clone contained an insert of approximately 2000 bp and expressed unique 200 and 53 kDa proteins that reacted with monospecific anti-adhesin antibody. The 200 kDa protein also reacted with anti-.beta.-galactosidase IgG, indicating that it is a fusion protein of which 84 kDa represents the streptococcal adhesin. The 84 and 53 kDa proteins are similar in size to the major polypeptides in a streptococcal antigen complex which is associated with the adhesion of G9B to saliva-coated hydroxyapatite. The 53 kDa fragment may result from post-translational cleavage of the recombinant polypeptide.