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Infection and Immunity, December 2001, p. 7402-7412, Vol. 69, No. 12
Laboratory of Bacterial Pathogenesis and
Immunology, The Rockefeller University, New York, New York
10021,1 and Public Health Research
Institute, New York, New York 100162
Received 27 July 2001/Returned for modification 28 August
2001/Accepted 7 September 2001
The first step in the colonization of group A streptococci
(Streptococcus pyogenes) is adherence to pharyngeal
epithelial cells. Prior to adherence to their target tissue, the first
barrier that the streptococci encounter is the mucous layer of the
respiratory tract. The present study was undertaken to characterize the
interaction between mucin, the major glycoprotein component of mucus,
and streptococci. We report here that S. pyogenes is able
to bind to bovine submaxillary mucin in solid-phase microtiter plate
assays. Western blots probed with 125I-labeled mucin and a
panel of monoclonal antibodies revealed that the streptococcal M
protein is one of two cell wall-associated proteins responsible for
this binding. The binding was further localized to the N-terminal
portion of the M molecule. Further analysis revealed that the M protein
binds to the sialic acid moieties on mucin, and this interaction seems
to be based on M-protein conformation rather than specific amino acid
sequences. We found that sialic acid also plays a critical role in the
adherence of an M6 streptococcal strain to the Detroit 562 human
pharyngeal cell line and have identified
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.12.7402-7412.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Group A Streptococci Bind to Mucin and Human
Pharyngeal Cells through Sialic Acid-Containing Receptors
2-6-linked sialic acid as
an important sialylated linkage for M-protein recognition. Western blot
analysis of extracted pharyngeal cell membrane proteins identified
three potential sialic acid-containing receptors for the M protein. The
results are the first to show that sialic acid not only is involved in
the binding of the streptococci to mucin but also plays an important
role in adherence of group A streptococci to the pharyngeal cell surface.
*
Corresponding author. Mailing address: Laboratory of
Bacterial Pathogenesis and Immunology, The Rockefeller University, 1230 York Ave., New York, NY 10021. Phone: (212) 327-8165. Fax: (212) 327-7584. E-mail: ryanp{at}mail.rockefeller.edu.
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