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  • 1
    Electronic Resource
    Electronic Resource
    Subunit structure of high molecular weight mouse nerve growth factor (1988)
    s.l. : American Chemical Society
    Biochemistry 27 (1988), S. 6675-6681 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00418a005
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  • 2
    Electronic Resource
    Electronic Resource
    Different alleles of the fcrA/mrp gene of Streptococcus pyogenes encode M-related proteins exhibiting an identical immunoglobulin-binding pattern (1996)
    Springer
    Medical microbiology and immunology 185 (1996), S. 39-47 
    Details
    ISSN: 1432-1831
    Keywords: Key words  Streptococcus pyogenes ; vir regulon ; M-related proteins ; Immunoglobulin-binding proteins ; Recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract   The majority of group A streptococci (GAS, Streptococcus pyogenes) express immunoglobulin (Ig)-binding proteins. The genes encoding these proteins belong either to the emm or the emm-related (fcrA/mrp and enn) gene family and are located in close proximity on the GAS genome, where they form part of the vir regulon. In the present study analysis of sequence data of the 5′ terminal portions of the fcrA/mrp genes from GAS isolates representing 37 different M serotypes led to a classification of six different types. Thus, although fcrA/mrp genes exhibit an allelic polymorphism, they do not display the high degree of N-terminal sequence diversity found among emm genes. The nucleotide sequences of the fcrA/mrp genes from 3 GAS isolates, belonging to serotypes M8, M9, and M13 and representing newly characterized fcrA/mrp gene types, are reported. Analysis of the Ig-binding properties of recombinant FcrA/Mrp8, 9, and 13 proteins, demonstrated a similar Ig-binding profile being reactive with human IgG subclasses 1, 2, and 4. This pattern is identical to that previously described for other recombinant fcrA/mrp4, 49, 64/14 and 76 gene products, indicating that this property is not affected by the N-terminal variability. Evidence for recombination between an fcrA/mrp and an mga gene was observed in an M-type 33 strain isolate providing further support for the concept of gene rearrangement contributing to the diversity of vir regulon gene products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004300050013
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  • 3
    Electronic Resource
    Electronic Resource
    M-related protein (Mrp) contributes to group A streptococcal resistance to phagocytosis by human granulocytes (1996)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 19 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The M protein has been postulated to be a major group A streptococcal (GAS) virulence factor because of its contribution to the bacterial resistance to opsono-phagocytosis. Direct evidence of this was only provided for GAS strains which expressed a single M protein. The majority of GAS express additional, structurally similar M-related proteins, Mrp and Enn, which have been described as IgG- and IgA-binding proteins. To determine the involvement of Mrp and M protein in phagocytosis resistance, the mrp and emm genes from serotypes M2, M4, and M49 as well as from M-untypeable strain 64/14 were insertionally inactivated. The mrp and emm mutants were subjected to direct bactericidal assays. As judged by numbers of surviving colony-forming units, all mutant strains with the exception of the mrp4 mutant exhibited reduced multiplication factors as compared to the isogenic wild-type strains. Subsequent analysis of phagocytosis by flow cytometry, measuring association of BCECF/AM-labelled bacteria and granulocytes, paralleled the results from direct bactericidal assays regardless of whether isolated granulocytes or whole blood were utilized. Resistant wild-type GAS strains bound to less than 24% of granulocytes, whereas phagocytosis-sensitive controls attached to more than 90% of the white blood cells. 40 to 60% of the granulocytes associated with the mrp and emm mutants within 1 h of co-incubation. Kinetic data suggested that attachment to granulocytes proceeds faster for emm mutants than for corresponding mrp mutants. By adding a dihydro-rhodamine123 stain and measuring fluorescence induced by oxidative burst, the experimental data suggested that bacteria bound to granulocytes were also engulfed and integrated into phagolysosomes. Thus, these data indicated that, if present, both mrp and emm gene products contribute to phagocytosis resistance by decreasing bacterial binding to granulocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1996.377910.x
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  • 4
    Electronic Resource
    Electronic Resource
    Group A streptococcal growth phase-associated virulence factor regulation by a novel operon (Fas) with homologies to two-component-type regulators requires a small RNA molecule (2001)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 39 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A novel growth phase-associated two-component-type regulator, Fas (fibronectin/fibrinogen binding/haemolytic activity/streptokinase regulator), of Streptococcus pyogenes was identified in the M1 genome sequence, based on homologies to the histidine protein kinase (HPK) and response regulator (RR) part of the Staphylococcus aureus Agr and Streptococcus pneumoniae Com quorum-sensing systems. The fas operon, present in all 12 tested M serotypes, was transcribed as polycystronic message (fasBCA) and contained genes encoding two potential HPKs (FasB and FasC) and one RR (FasA). Downstream of fasBCA, we identified a small 300 nucleotide monocistronic transcript, designated fasX, that did not appear to encode true peptide sequences. Measurements of luciferase promoter fusions revealed a growth phase-associated transcription of fasBCA and fasX, with peak activities during the late exponential phase. Insertional mutagenesis disrupting fasBCA and fasA led to a phenotype similar to agr-null mutations in S. aureus, with prolonged expression of extracellular matrix protein-binding adhesins and reduced expression of secreted virulence factors such as streptokinase and streptolysin S. In addition, fasX transcription was dependent on the RR FasA; however, deletion mutagenesis of fasX resulted in a similar phenotype to that of the fasBCA or fasA mutants. Complementation of the fasX deletion mutant, with the fasX gene expressed in trans from a plasmid, restored the wild-type fasBCA regulation pattern. This strongly suggested that fasX, a putative non-translated RNA, is the main effector molecule of the fas regulon. However, using spent culture supernatants from wild-type and fas mutant strains, we were not able to show an influence on the logarithmic growth phase expression of fas and dependent genes. Thus, despite structural and functional similarities between fas and agr, to date the fas operon appears not to be involved in group A streptococcal (GAS) quorum-sensing regulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02226.x
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  • 5
    Electronic Resource
    Electronic Resource
    Is the membrane attack complex of complement an enzyme? (1984)
    Springer
    Molecular and cellular biochemistry 61 (1984), S. 5-15 
    Details
    ISSN: 1573-4919
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary Recent studies on the functional activities of the membrane attack complex of complement, C5b-9, are reviewed. A new speculative hypothesis has been advanced to account for the ability of complement to mediate lysis of various targets. This hypothesis has three major elements: 1) that the membrane attack complex is an enzyme; 2) that the substrate for this putative enzyme is a membrane constituent; 3) that the substrate specificity of the putative enzyme is dependent on the species source of individual complement components within the C5b-9 complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239603
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  • 6
    Electronic Resource
    Electronic Resource
    Reactivity of bacterial Fc receptors with bovine immunoglobulins: implications and limitations for quantitative immunochemistry (1987)
    Springer
    Applied microbiology and biotechnology 27 (1987), S. 168-173 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The interaction of bovine immunoglobulins with staphylococcal Protein A and a group C streptococcal bacterial Fc receptor (FcRc) were compared. The isolated group C streptococcal receptor was reactive with both bovine IgG1 and IgG2. The reactivity of the streptococcal FcRc with IgG2 was approximately 40 fold greater than that observed with IgG1. By contrast, protein A reacted only poorly with bovine IgG2 and no detectable reactivity was observed with IgG1. A two stage competitive binding assay to measure bovine IgG in serum and secretions using 125I-labeled protein A as tracer was developed. This assay was found to be sensitive and reproducible and was used to measure serum IgG levels in cattle of differing ages and breeds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00251940
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  • 7
    Electronic Resource
    Electronic Resource
    Isolation and partial characterization of a type II Fe receptor from a group A streptococcus (1986)
    Springer
    Molecular and cellular biochemistry 70 (1986), S. 57-66 
    Details
    ISSN: 1573-4919
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A group A streptococcal strain rich in Fc receptors was selected by an immunoblotting technique and used as the source for isolation of a functionally active Fc receptor. A variety of extraction techniques were compared including (1) heat extraction at neutral, acid or alkaline pH, (2) treatment with the enzymes mutanolysin, hyaluronidase, trypsin, papain or phage lysin, or (3) autoclaving or heating in the presence of sodium dodecyl sulfate. The most homogeneous receptor was recovered following heat extraction and contained two molecular weight forms. The major form had a molecular weight of 56 000 daltons and the minor form had a molecular weight of 38 000 daltons. These two proteins could be isolated without loss of activity by binding to and elution from a column of immobilized human IgG. An antibody prepared against a single form of the affinity purified receptor demonstrated reactivity with both molecular weight forms of the heat extracted receptor. The group A receptor was found to be both antigenically and physicochemically distinct from either the type I receptor found on the majority of Staphylococcus aureus strains or the type III Fc receptors found on the majority of group C streptococcal strains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233803
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