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  • 1
    Electronic Resource
    Electronic Resource
    Adenylate cyclase activation by the .beta.-adrenergic receptors as a diffusion-controlled process (1979)
    s.l. : American Chemical Society
    Biochemistry 18 (1979), S. 846-853 
    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/bi00572a017
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  • 2
    Electronic Resource
    Electronic Resource
    Temperature dependence of .beta. receptor, adenosine receptor, and sodium fluoride stimulated adenylate cyclase from turkey erythrocytes (1980)
    s.l. : American Chemical Society
    Biochemistry 19 (1980), S. 4451-4460 
    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/bi00560a011
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  • 3
    Electronic Resource
    Electronic Resource
    De novo formation of focal complex-like structures in host cells by invading Streptococci (2001)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 41 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Group A streptococcus (GAS) induces its own entry into eukaryotic cells in vitro and in vivo. Fibronectin (Fn) bound to protein F1, a GAS surface protein, acts as a bridge connecting the bacterium to host cell integrins. This triggers clustering of integrins, which acquire a polar pattern of distribution similar to that of protein F1 on the GAS surface. A unique and transient adhesion complex is formed at the site of GAS entry, which does not contain α-actinin. Vinculin is recruited to the site of GAS entry but is not required for uptake. The invading GAS recruits focal adhesion kinase (FAK), which is required for uptake and is tyrosine phosphorylated. The Src kinases, Src, Yes and Fyn, enhance the efficiency of GAS uptake but are not absolutely required for GAS entry. In addition, Rac and Cdc42, but not Rho, are required for the entry process. We suggest a model in which integrin engagement by Fn-occupied protein F1 triggers two independent signalling pathways. One is initiated by FAK recruitment and tyrosine phosphorylation, whereas the other is initiated by the recruitment and activation of Rac. The two pathways subsequently converge to trigger actin rearrangement leading to bacterial uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02535.x
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  • 4
    Electronic Resource
    Electronic Resource
    A locus of group A streptococcus involved in invasive disease and DNA transfer (2002)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 46 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Group A streptococcus (GAS) causes diseases ranging from benign to severe infections such as necrotizing fasciitis (NF). The reasons for the differences in severity of streptococcal infections are unexplained. We developed the polymorphic-tag-lengths-transposon-mutagenesis (PTTM) method to identify virulence genes in vivo. We applied PTTM on an emm14 strain isolated from a patient with NF and screened for mutants of decreased virulence, using a mouse model of human soft-tissue infection. A mutant that survived in the skin but was attenuated in its ability to reach the spleen and to cause a lethal infection was identified. The transposon was inserted into a small open reading frame (ORF) in a locus termed sil, streptococcal invasion locus. sil contains at least five genes (silA-E) and is highly homologous to the quorum-sensing competence regulons of Streptococcus pneumoniae. silA and silB encode a putative two-component system whereas silD and silE encode two putative ABC transporters. silC is a small ORF of unknown function preceded by a combox promoter. Insertion and deletion mutants of sil had a diminished lethality in the animal model. Virulence of a deletion mutant of silC was restored when injected together with the avirulent emm14-deletion mutant, but not when these mutants were injected into opposite flanks of a mouse. DNA transfer between these mutants occurred in vivo but could not account for the complementation of virulence. DNA exchange between the emm14-deletion mutant and mutants of sil occurred also in vitro, at a frequency of ∼ 10-8 for a single antibiotic marker. Whereas silC and silD mutants exchanged markers with the emm14 mutant, silB mutant did not. Thus, we identified a novel locus, which controls GAS spreading into deeper tissues and could be involved in DNA transfer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.03127.x
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  • 5
    Electronic Resource
    Electronic Resource
    Expression of different group A streptococcal M proteins in an isogenic background demonstrates diversity in adherence to and invasion of eukaryotic cells (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 31 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The M protein of group A streptococcus (GAS) is considered to be a major virulence factor because it renders GAS resistant to phagocytosis and allows bacterial growth in human blood. There are more than 80 known serotypes of M proteins, and protective opsonic antibodies produced during disease in humans are serotype specific. M proteins also mediate bacterial adherence to epithelial cells of skin and pharynx. GAS strains vary in the genomic organization of the mga regulon, which contains the genes encoding M and M-like proteins and other virulence factors. This diversity of organization makes it difficult to assess virulence of M proteins of different serotypes, unless they can be expressed in an isogenic background. Here, we express M proteins of different serotypes in the M protein- and protein F1-deficient GAS strain, SAM2, which also lacks M-like proteins. Genes encoding M proteins of different serotypes (emmXs) have been integrated into the SAM2 chromosome in frame with the emm6.1 promoter and its mga regulon, resulting in similar levels of emmX expression. Although SAM2 exhibits a very low level of adherence to and invasion of HEp-2 and HaCaT cells, a SAM2-derived strain expressing M6 protein adheres to and invades both cell types. In contrast, the isogenic strain expressing M18 protein adheres to both cell types, but invades with a very low efficiency. A strain expressing M3 protein adheres to both types of cells, but its invasion of HEp-2 cells is serum dependent. A GAS strain expressing M6 protein does not compete with the isogenic strain expressing M18 protein for adherence to or invasion of HaCaT cells. We conclude that M proteins of different serotypes recognize different repertoires of receptors on the surfaces of eukaryotic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01289.x
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  • 6
    Electronic Resource
    Electronic Resource
    Protein translocation into host epithelial cells by infecting enteropathogenic Escherichia coli (1998)
    Oxford BSL : Blackwell Science Ltd, UK
    Molecular microbiology 28 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Enteropathogenic Escherichia coli (EPEC) causes diarrhoea in young children. EPEC induces the formation of actin pedestal in infected epithelial cells. A type III protein secretion system and several proteins that are secreted by this system, including EspB, are involved in inducing the formation of the actin pedestals. We have demonstrated that contact of EPEC with HeLa cells is associated with the induction of production and secretion of EspB. Shortly after infection, EPEC initiates translocation of EspB, and EspB fused to the CyaA reporter protein (EspB–CyaA), into the host cell. The translocated EspB was distributed between the membrane and the cytoplasm of the host cell. Translocation was strongly promoted by attachment of EPEC to the host cell, and both attachment factors of EPEC, intimin and the bundle-forming pili, were needed for full translocation efficiency. Translocation and secretion of EspB and EspB–CyaA were abolished in mutants deficient in components of the type III protein secretion system, including sepA and sepB mutants. EspB–CyaA was secreted but not translocated by an espB mutant. These results indicate that EspB is both translocated and required for protein translocation by EPEC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00782.x
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  • 7
    Electronic Resource
    Electronic Resource
    Roles of integrins and fibronectin in the entry of Streptococcus pyogenes into cells via protein F1 (1998)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 30 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Entry of group A streptococcus (GAS) into cells has been suggested as an important trait in GAS pathogenicity. Protein F1, a fibronectin (Fn) binding protein, mediates GAS adherence to cells and the extracellular matrix, and efficient cell internalization. We demonstrate that the cellular receptors responsible for protein F1-mediated internalization of GAS are integrins capable of Fn binding. In HeLa cells, bacterial entry is blocked by anti-β1 integrin monoclonal antibody. In the mouse cell line GD25, a β1 null mutant, the αvβ3 integrin promotes GAS entry. Internalization of these cells by GAS is blocked by a peptide that specifically binds to αvβ3 integrin. In both cell lines, entry of GAS requires the occupancy of protein F1 by Fn. Neither the 29 kDa nor the 70 kDa N-terminal fragments or the 120 kDa cell-binding fragment of Fn promote bacterial entry. Fn-coated beads are taken up efficiently by HeLa cells. Both the entry of GAS via protein F1 and the uptake of Fn-coated beads are blocked by anti-β1 antibody but are unaffected by a large excess of soluble Fn. Internalization of HeLa cells by bacteria bearing increasing amounts of prebound Fn to protein F1 reveals a sigmoidal ultrasensitive curve. These suggest that the ability of particles to interact via Fn with multiple integrin sites plays a central role in their ability to enter cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01097.x
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  • 8
    Electronic Resource
    Electronic Resource
    Protein F2, a novel fibronectin-binding protein from Streptococcus pyogenes, possesses two binding domains (1996)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 21 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Binding of the group A streptococcus (GAS) to respiratory epithelium is mediated by the fibronectin (Fn)-binding adhesin, protein F1. Previous studies have suggested that certain GAS strains express Fn-binding proteins that are different from protein F1. In this study, we have cloned, sequenced, and characterized a gene (prtF2) from GAS strain 100076 encoding a novel Fn-binding protein, termed protein F2. Insertional inactivation of prtF2 in strain 100076 abolishes its high-affinity Fn binding. prtF2-related genes exist in most GAS strains that lack prtF1 (encoding protein F1) but bind Fn with high affinity. These observations suggest that protein F2 is a major Fn-binding protein in GAS. Protein F2 is highly homologous to Fn-binding proteins from Streptococcus dysgalactiae and Strep-tococcus equisimilis, particularly in its carboxy-terminal portion. Two domains are responsible for Fn binding by protein F2. One domain (FBRD) consists of three consecutive repeats, whereas the other domain (UFBD) resides on a non-repeated stretch of approximately 100 amino acids and is located 100 amino acids amino-terminal of FBRD. Each of these domains is capable of binding Fn when expressed as a separate protein. In strain 100076, protein F2 activity is regulated in response to alterations in the concentration of atmospheric oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1996.6331356.x
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  • 9
    Electronic Resource
    Electronic Resource
    Protein F: an adhesin of Streptococcus pyogenes binds fibronectin via two distinct domains (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 10 (1993), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The binding of Streptococcus pyogenes to fibronectin (FN) enables the adherence of this pathogen to target epithelial cells, which is the first necessary step for initiation of infection. Binding is mediated by a bacterial surface protein termed protein F. Here we provide the complete structure of protein F and identify two domains responsible for binding to fibronectin. The first domain is located towards the C-terminal end of the molecule and is composed of five repeats of 37 amino acids that are completely repeated four times and a fifth time partially. The second domain is adjacent to the first domain and is located on the /V-terminal side of it. It is composed of a single stretch of 43 amino acids. Protein F expressed in Escherichia coli completely blocked the binding of fibronectin to S. pyogenes. However, mutant proteins that contained only one or the other of the two domains were only capable of partial blockage of binding. Complete blockage of binding of fibronectin could be achieved when a protein extract containing the N-terminal domain was mixed in a binding reaction with a protein extract containing the C-terminal domain. Similarly, a purified recombinant protein containing the two domains only, blocked the binding completely. In contrast, a purified recombinant protein containing just the C-terminal domain, blocked the binding partially. A clone exclusively expressing the C-terminal domain, completely blocked the binding of the 30 kDa N-terminal fragment of fibronectin to S. pyogenes, whereas a clone expressing the N-terminal domain failed to block the binding of this FN fragment. Thus, the two FN-binding domains of protein F are necessary for maximal bacterial binding and act in concert to enhance the binding to fibronectin. The possibility that the two domains bind to two different regions on the fibronectin molecule is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1993.tb00975.x
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  • 10
    Electronic Resource
    Electronic Resource
    Adherence and fibronectin binding are environmentally regulated in the group A streptococci (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 9 (1993), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The ability of the pathogenic Gram-positive bacterium Streptococcus pyogenes (group A streptococcus) to bind fibronectin and adhere to respiratory epithelial cells is dependent on a surface protein called protein F. In this study, we have examined the regulation of expression of protein F and have shown that it is environmentally regulated in response to alterations in atmosphere. In six recent clinical isolates, expression of protein F was repressed during growth under reduced concentrations of O2. Expression in an anaerobic environment was induced by both superoxide-generating and redox-altering reagents. However, regulation did not involve mry, a gene that controls expression of several streptococcal surface proteins. Protein F was constitutively expressed in one of two laboratory-passaged strains analysed, and in a complementation analysis using an allele of the gene that encodes protein F (prtF) cloned from a regulated strain and expressed in a constitutive strain, the constitutive phenotype was shown to be dominant in trans. Regulation, as monitored by fusion of prtF to a promoterless chloramphenicol acetyltransferase gene, involved transcriptional control. Environmentally induced alterations in protein F expression affected the ability of the bacterium to adhere to epithelial cells, which suggests that the ability to regulate expression of protein F may be important during infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1993.tb01250.x
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