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Ig-binding bacterial proteins also bind proteinase inhibitors

Sjöbring, U LU ; Trojnar, J ; Grubb, A LU ; Akerström, B LU and Björck, L LU (1989) In Journal of immunology (Baltimore, Md. : 1950) 143(9). p.54-2948
Abstract

Protein G is a streptococcal cell wall protein with separate binding sites for IgG and human serum albumin (HSA). In the present work it was demonstrated that alpha 2-macroglobulin (alpha 2M) and kininogen, two proteinase inhibitors of human plasma, bound to protein G, whereas 23 other human proteins showed no affinity. alpha 2M was found to interact with the IgG-binding domains of protein G, and in excess alpha 2M inhibited IgG binding and vice versa. A synthetic peptide, corresponding to one of the homologous IgG-binding domains of protein G, blocked binding of protein G to alpha 2M. Protein G showed affinity for both native and proteinase complexed alpha 2M but did not bind to the reduced form of alpha 2M, or to the C-terminal domain... (More)

Protein G is a streptococcal cell wall protein with separate binding sites for IgG and human serum albumin (HSA). In the present work it was demonstrated that alpha 2-macroglobulin (alpha 2M) and kininogen, two proteinase inhibitors of human plasma, bound to protein G, whereas 23 other human proteins showed no affinity. alpha 2M was found to interact with the IgG-binding domains of protein G, and in excess alpha 2M inhibited IgG binding and vice versa. A synthetic peptide, corresponding to one of the homologous IgG-binding domains of protein G, blocked binding of protein G to alpha 2M. Protein G showed affinity for both native and proteinase complexed alpha 2M but did not bind to the reduced form of alpha 2M, or to the C-terminal domain of the protein known to interact with alpha 2M receptors on macrophages. Binding of protein G to alpha 2M and kininogen did not interfere with their inhibitory activity on proteinases, and the interaction between protein G and the two proteinase inhibitors was not due to proteolytic activity of protein G. The finding that protein G has affinity for proteinase inhibitors was generalized to comprise also other Ig binding bacterial proteins. Thus, alpha 2M and kininogen, were shown to bind both protein A of Staphylococcus aureus and protein L of Peptococcus magnus. The results described above suggest that Ig-binding proteins are involved in proteolytic events, which adds a new and perhaps functional aspect to these molecules.

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organization
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published
subject
keywords
Bacterial Proteins/metabolism, In Vitro Techniques, Kininogens/metabolism, Lymphokines/metabolism, Molecular Weight, Nerve Tissue Proteins/metabolism, Prostatic Secretory Proteins, Protease Inhibitors/metabolism, Protein Binding, Streptococcus, Trypsin/metabolism, alpha-Macroglobulins/metabolism
in
Journal of immunology (Baltimore, Md. : 1950)
volume
143
issue
9
pages
54 - 2948
publisher
American Association of Immunologists
external identifiers
  • pmid:2478629
  • scopus:0024451422
ISSN
0022-1767
language
English
LU publication?
yes
id
37c830ca-708a-44aa-8c53-a41d901aa896
alternative location
https://www.jimmunol.org/content/143/9/2948.long
date added to LUP
2019-05-22 10:29:39
date last changed
2020-01-13 01:52:03
@article{37c830ca-708a-44aa-8c53-a41d901aa896,
  abstract     = {<p>Protein G is a streptococcal cell wall protein with separate binding sites for IgG and human serum albumin (HSA). In the present work it was demonstrated that alpha 2-macroglobulin (alpha 2M) and kininogen, two proteinase inhibitors of human plasma, bound to protein G, whereas 23 other human proteins showed no affinity. alpha 2M was found to interact with the IgG-binding domains of protein G, and in excess alpha 2M inhibited IgG binding and vice versa. A synthetic peptide, corresponding to one of the homologous IgG-binding domains of protein G, blocked binding of protein G to alpha 2M. Protein G showed affinity for both native and proteinase complexed alpha 2M but did not bind to the reduced form of alpha 2M, or to the C-terminal domain of the protein known to interact with alpha 2M receptors on macrophages. Binding of protein G to alpha 2M and kininogen did not interfere with their inhibitory activity on proteinases, and the interaction between protein G and the two proteinase inhibitors was not due to proteolytic activity of protein G. The finding that protein G has affinity for proteinase inhibitors was generalized to comprise also other Ig binding bacterial proteins. Thus, alpha 2M and kininogen, were shown to bind both protein A of Staphylococcus aureus and protein L of Peptococcus magnus. The results described above suggest that Ig-binding proteins are involved in proteolytic events, which adds a new and perhaps functional aspect to these molecules.</p>},
  author       = {Sjöbring, U and Trojnar, J and Grubb, A and Akerström, B and Björck, L},
  issn         = {0022-1767},
  language     = {eng},
  month        = {11},
  number       = {9},
  pages        = {54--2948},
  publisher    = {American Association of Immunologists},
  series       = {Journal of immunology (Baltimore, Md. : 1950)},
  title        = {Ig-binding bacterial proteins also bind proteinase inhibitors},
  url          = {https://www.jimmunol.org/content/143/9/2948.long},
  volume       = {143},
  year         = {1989},
}