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Allosteric and temperature effects on the plasma protein binding by streptococcal M protein family members

Cedervall, T LU ; Akesson, P ; Stenberg, L LU ; Herrmann, A LU and Akerström, B LU (1995) In Scandinavian Journal of Immunology 42(4). p.41-433
Abstract

Most group A streptococcal strains bind immunoglobulins (Ig) and fibrinogen to their cell walls. It is shown in this paper that the Ig-binding of three different strains was much weaker at 37 degrees C than at room temperature (20 degrees C), whereas the fibrinogen binding was unaffected by temperature. The binding properties and molecular sizes of two purified group A streptococcal cell surface proteins from the M protein family were studied at various temperatures, M1 protein with affinity for IgG, fibrinogen and albumin, and protein Sir22 with affinity for IgA and IgG. Both proteins appeared as monomers which bound all their ligands, including fibrinogen, very weakly at 37 degrees C, and as strongly binding dimers at 10 and 20... (More)

Most group A streptococcal strains bind immunoglobulins (Ig) and fibrinogen to their cell walls. It is shown in this paper that the Ig-binding of three different strains was much weaker at 37 degrees C than at room temperature (20 degrees C), whereas the fibrinogen binding was unaffected by temperature. The binding properties and molecular sizes of two purified group A streptococcal cell surface proteins from the M protein family were studied at various temperatures, M1 protein with affinity for IgG, fibrinogen and albumin, and protein Sir22 with affinity for IgA and IgG. Both proteins appeared as monomers which bound all their ligands, including fibrinogen, very weakly at 37 degrees C, and as strongly binding dimers at 10 and 20 degrees C. Furthermore, the results demonstrated that the plasma protein binding of the bacterial proteins was allosterically regulated, i.e. the binding of a ligand to one site modulated the binding of a ligand to a second site. For example, the binding of albumin or IgG to purified M1 protein at 10 and 20 degrees C strongly enhanced the binding of fibrinogen at 37 degrees C. This indicates that the high affinity dimer form of the bacterial proteins can be stabilized at 37 degrees C, a possible explanation for the strong fibrinogen binding of whole bacteria. Finally, the sizes and binding properties of three M1 protein fragments were studied and the results indicated that the centrally located C-repeats, which are conserved among the members of the M protein family, are important for the formation of the high-affinity dimers of the bacterial proteins.

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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Allosteric Regulation, Antigens, Bacterial, Bacterial Outer Membrane Proteins/chemistry, Blood Proteins/chemistry, Carrier Proteins/chemistry, Humans, Streptococcus/metabolism, Temperature
in
Scandinavian Journal of Immunology
volume
42
issue
4
pages
41 - 433
publisher
Wiley-Blackwell
external identifiers
  • scopus:0028839780
  • pmid:7569776
ISSN
0300-9475
DOI
10.1111/j.1365-3083.1995.tb03677.x
language
English
LU publication?
yes
id
bd04078e-506b-47e7-9802-20f2c38644b0
date added to LUP
2019-05-22 10:19:43
date last changed
2024-06-12 15:58:02
@article{bd04078e-506b-47e7-9802-20f2c38644b0,
  abstract     = {{<p>Most group A streptococcal strains bind immunoglobulins (Ig) and fibrinogen to their cell walls. It is shown in this paper that the Ig-binding of three different strains was much weaker at 37 degrees C than at room temperature (20 degrees C), whereas the fibrinogen binding was unaffected by temperature. The binding properties and molecular sizes of two purified group A streptococcal cell surface proteins from the M protein family were studied at various temperatures, M1 protein with affinity for IgG, fibrinogen and albumin, and protein Sir22 with affinity for IgA and IgG. Both proteins appeared as monomers which bound all their ligands, including fibrinogen, very weakly at 37 degrees C, and as strongly binding dimers at 10 and 20 degrees C. Furthermore, the results demonstrated that the plasma protein binding of the bacterial proteins was allosterically regulated, i.e. the binding of a ligand to one site modulated the binding of a ligand to a second site. For example, the binding of albumin or IgG to purified M1 protein at 10 and 20 degrees C strongly enhanced the binding of fibrinogen at 37 degrees C. This indicates that the high affinity dimer form of the bacterial proteins can be stabilized at 37 degrees C, a possible explanation for the strong fibrinogen binding of whole bacteria. Finally, the sizes and binding properties of three M1 protein fragments were studied and the results indicated that the centrally located C-repeats, which are conserved among the members of the M protein family, are important for the formation of the high-affinity dimers of the bacterial proteins.</p>}},
  author       = {{Cedervall, T and Akesson, P and Stenberg, L and Herrmann, A and Akerström, B}},
  issn         = {{0300-9475}},
  keywords     = {{Allosteric Regulation; Antigens, Bacterial; Bacterial Outer Membrane Proteins/chemistry; Blood Proteins/chemistry; Carrier Proteins/chemistry; Humans; Streptococcus/metabolism; Temperature}},
  language     = {{eng}},
  number       = {{4}},
  pages        = {{41--433}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Scandinavian Journal of Immunology}},
  title        = {{Allosteric and temperature effects on the plasma protein binding by streptococcal M protein family members}},
  url          = {{http://dx.doi.org/10.1111/j.1365-3083.1995.tb03677.x}},
  doi          = {{10.1111/j.1365-3083.1995.tb03677.x}},
  volume       = {{42}},
  year         = {{1995}},
}