Many group A streptococcal strains express two different immunoglobulin‐binding proteins, encoded by closely linked genes: characterization of the proteins expressed by four strains of different M‐type

Stenberg, Lars; O’Toole, Paul W.; Lindahl, Gunnar

doi:10.1111/j.1365-2958.1992.tb01557.x

Cited by 107 publications

(111 citation statements)

References 31 publications

(44 reference statements)

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“…Other Methods and Reagents-Radiolabeling of proteins with carrierfree 125 I (Amersham Biosciences) by the chloramine-T method, and Western blot analysis was performed as described (28). High molecular mass heparin (average molecular mass 14 kDa) was purchased from Leo Pharma (Malmö, Sweden).…”

Section: Methodsmentioning

confidence: 99%

Streptococcal β Protein Has Separate Binding Sites for Human Factor H and IgA-Fc

Areschoug

Stålhammar‐Carlemalm

Karlsson

et al. 2002

Journal of Biological Chemistry

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The group B streptococcus (GBS) is the most important cause of life-threatening bacterial infections in newborn infants. Protective immunity to GBS infection is elicited by several surface proteins, one of which, the ␤ protein, is known to bind human IgA-Fc. Here, we show that the ␤ protein also binds human factor H (FH), a negative regulator of complement activation. Absorption experiments with whole human plasma demonstrated binding of FH to a GBS strain expressing ␤ protein but not to an isogenic ␤-negative mutant. This binding was due to a direct interaction between ␤ and FH, as shown by experiments with purified proteins. Inhibition tests and studies with ␤ fragments demonstrated that FH and IgA-Fc bind to separate and nonoverlapping regions in ␤. Heparin, a known ligand for FH, specifically inhibited the binding between ␤ and FH, suggesting that FH has overlapping binding sites for ␤ and heparin. Bacteria-bound FH retained its complement regulatory activity, implying that ␤-expressing GBS may use bound FH to evade complement attack. The finding that ␤ protein binds FH adds to a growing list of interactions between human pathogens and complement regulatory proteins, supporting the notion that these interactions are of general importance in bacterial pathogenesis.

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Section: Methodsmentioning

confidence: 99%

Streptococcal β Protein Has Separate Binding Sites for Human Factor H and IgA-Fc

Areschoug

Stålhammar‐Carlemalm

Karlsson

et al. 2002

Journal of Biological Chemistry

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“…A C5a peptidase molecule, located on the cell surface, is able to cleave and inactivate the C5a chemotactic factor of complement to prevent recruitment of PMNs and macrophages to the site of infection (64,65). Many GAS strains produce M-like proteins on their surface that are similar in structure to M protein and are able to bind the Fc portion of immunoglobulins A and/or G (14,58). In addition to cell surface products, GAS also secretes numerous virulence-associated exoproducts.…”

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confidence: 99%

Role of mga in growth phase regulation of virulence genes of the group A streptococcus

1997

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To determine whether growth phase affects the expression of mga and other virulence-associated genes in the group A streptococcus (GAS), total RNA was isolated from the serotype M6 GAS strain JRS4 at different phases of growth and transcript levels were quantitated by hybridization with radiolabeled DNA probes. Expression of mga (which encodes a multiple gene regulator) and the Mga-regulated genes emm (which encodes M protein) and scpA (which encodes a complement C5a peptidase) was found to be maximal in exponential phase and shut off as the bacteria entered stationary phase, while the housekeeping genes recA and rpsL showed constant transcript levels over the same period of growth. Expression of mga from a foreign phage promoter in a mga-deleted GAS strain (JRS519) altered the wild-type growth phase-dependent transcription profile seen for emm and scpA, as well as for mga. Therefore, the temporal control of mga expression requires its upstream promoter region, and the subsequent growth phase regulation of emm and scpA is Mga dependent. A number of putative virulence genes in JRS4 were shown not to require Mga for their expression, although several exhibited growth phase-dependent regulation that was similar to mga, i.e., slo (which encodes streptolysin O) and plr (encoding the plasmin receptor/glyceraldehyde-3-phosphate dehydrogenase). Still others showed a markedly different pattern of expression (the genes for the superantigen toxins MF and SpeC). These results suggest the existence of complex levels of global regulation sensitive to growth phase that directly control the expression of virulence genes and mga in GAS.

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“…It is known that the FcRA proteins of some OF-positive Protein F of S. pyogenes serotypes of S. pyogenes bind fibrinogen in addition to IgG (Stenberg et al, 1992). From the present strain of serotype M1.5, the gene for the FcRA protein was cloned and sequenced (Katerov et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

Protein F, a fibronectin-binding protein of Streptococcus pyogenes, also binds human fibrinogen: isolation of the protein and mapping of the binding region

et al. 1998

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Summary: During screening of a gene library of Streptococcus pyogenes type M15 for fibrinogen-binding material, a protein of approximately 100 kDa, encoded outside the vir region, was found. DNA sequencing revealed this component to be identical to protein F, a fibronectin-binding protein. Isolation of the recombinant protein, termed F15, was performed by the use of fibrinogen affinity chromatography. The affinity constant (K a) of protein F15 for fibrinogen, 1.25 x 107 mol−1, was lower than that for fibronectin, 1.8 x 108 mol−1. The fibrinogen-binding domain was located in the N-terminal part of the molecule, while the fibronectin-binding domains, as previously determined, were in the C-terminal portion of protein F. To examine the amino acid sequence heterogeneity of protein F, the 5′ part of the prtF gene, corresponding to the N-terminal variable region of the protein, was amplified by PCR from 12 strains of S. pyogenes belonging to six different M-types. Alignment of these nucleotide sequences indicated that the 5′ portion of the prtF gene had probably undergone a number of intragenic recombination and horizontal gene transfer events, allowing a pattern of structural diversity of protein F observed earlier for some other streptococcal virulence factors. There was no strict correlation between M-type and nucleotide sequence of the variable region of the prtF gene and, compared to streptococcal M protein, the overall variation observed for protein F appeared more limited.

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Many group A streptococcal strains express two different immunoglobulin‐binding proteins, encoded by closely linked genes: characterization of the proteins expressed by four strains of different M‐type

Cited by 107 publications

References 31 publications

Streptococcal β Protein Has Separate Binding Sites for Human Factor H and IgA-Fc

Streptococcal β Protein Has Separate Binding Sites for Human Factor H and IgA-Fc

Role of mga in growth phase regulation of virulence genes of the group A streptococcus

Protein F, a fibronectin-binding protein of Streptococcus pyogenes, also binds human fibrinogen: isolation of the protein and mapping of the binding region

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