Previous Article | Next Article ![]()
Infect. Immun., 07 1996, 2787-2793, Vol 64, No. 7
PG Jerlstrom, SR Talay, P Valentin-Weigand, KN Timmis and GS Chhatwal
The beta-antigen of the c protein complex of group B streptococci contains
two immunoglobulin A (IgA)-binding domains called A and B. A 73-amino-acid
segment in domain A is responsible for most of the IgA- binding activity.
To identify the IgA binding motif, the 73-amino-acid domain was divided
into 60 14-amino-acid overlapping peptides spot synthesized onto a
cellulose membrane. A 20-residue putative antigenic epitope was identified
and expressed as a fusion protein. The fusion protein was purified by fast
protein liquid chromatography and used to raise rabbit antiserum. By use of
a membrane with spot-synthesized peptide amino acids of decreasing length
(from 14 to 6 amino acids), the major antigenic epitope recognized by the
anti-fusion protein antibodies was mapped to motif MLKKIE. Anti-fusion
protein antibodies inhibited the binding of IgA to group B streptococci.
This inhibition could be blocked by the peptide containing the motif
MLKKIE. These results indicate that the motif MLKKIE is located in the
IgA-binding site. The IgA-binding domain of beta-antigen from three group B
streptococcal strains reacted with the anti-fusion protein antibodies, and
their coding sequences gave positive signals in Southern hybridization. The
sequences of beta-antigen from these strains were amplified by PCR, and
sequence analysis showed them to be identical. The results indicate that
the motif MLKKIE is required for IgA binding and is present in different
group B streptococcal strains.
Copyright © 1996, American Society for Microbiology
Identification of an immunoglobulin A binding motif located in the beta- antigen of the c protein complex of group B streptococci
Department of Microbiology, Technical University/GBF-National Research Centre for Biotechnology, Braunschweig, Germany.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»