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  • 1
    Electronic Resource
    Electronic Resource
    An Algorithm for Identifying Similar Amino Acid Clusters among Different Alpha-Helical Coiled-Coil Proteins Using Their Secondary Structure (1999)
    Springer
    Algorithmica 25 (1999), S. 330-346 
    Details
    ISSN: 1432-0541
    Keywords: Key words. Computational biology, Protein structure, Coiled-coil, Epitope, Dynamic programming.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. We describe a simple approach for finding identical amino acid clusters on the outer surface of α -helical coiled-coil proteins by examining the sequence of amino acids that compose the protein. Finding such similarities is an important immunological problem, since these may correspond to cross-reactive epitopes, i.e., sites at which antibodies produced against one protein also bind to another conformationally similar protein. Because of the regularities inherent in a coiled-coil structure the position of each amino acid on the structure is predicted. Based on this prediction, our algorithm finds similarities on the outer surface of the proteins. The matches found by our algorithm serve as an important screening process, intended to indicate which experiments to conduct to determine sites that correspond to cross-reactive epitopes. The location of several cross-reactive epitopes between M proteins and myosins had been verified experimentally. Although our approach makes many simplifying assumptions, these epitopes always correspond to clusters of identical amino acids, which our algorithm predicted to be contiguous on the outer surface. Our algorithm runs in O(n+m+r) time and O(n+m) space, where n and m are the lengths of the protein sequences, and r is the number of matching amino acids that appear in the same structural position of the α -helix in both sequences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008281
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  • 2
    Electronic Resource
    Electronic Resource
    Stronger Proliferative Response to Membrane Versus Cell-Wall Streptococcal Proteins by Peripheral Blood T Cells in Chronic Plaque Psoriasis (2001)
    Oxford, UK : Blackwell Science Ltd
    Scandinavian journal of immunology 54 (2001), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Proliferative responses of peripheral blood mononuclear cells (PBMC) to group A streptococcal (GAS) antigens have been studied in 24 patients with psoriasis and 15 disease controls. Extracts of cell wall (including M protein) from types M4 and M12 GAS, recombinant M6 protein, and both cell-wall and cell-membrane extracts from type M6 (M6+) GAS and its corresponding M gene deletion mutant (M6-) were tested. PBMC from psoriatic patients proliferated more strongly to cell-wall extracts from M12 versus M4 (P = 0.0348), and to M6+ versus M6- (P = 0.0019) GAS with, in most cases, moderate proliferation to recombinant M6 protein. The psoriatic response to M12 cell wall was significantly increased compared to the controls (P = 0.0032). In psoriatics, M6+ membrane extracts induced a markedly greater proliferation than those of cell wall (P = 0.0002); responses to M6+ (P = 0.0039) and M6- (P = 0.0114) membrane extracts were higher than those of the control PBMC. Both groups showed a decreased response to the M6- versus M6+ membrane extracts (P = 0.0030; P= 0.0181, respectively). This study has demonstrated that patients with psoriasis have a heightened circulating T-cell response to cell wall M protein and to non-M proteins present on the cell wall and membrane of GAS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3083.2001.01009.x
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  • 3
    Electronic Resource
    Electronic Resource
    Selective Response of Dermal Th-1 Cells to 20–50 kDa Streptococcal Cell-Wall Proteins in Chronic Plaque Psoriasis (2003)
    Oxford, UK : Blackwell Science Ltd
    Scandinavian journal of immunology 58 (2003), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have recently described a dermal Th-1 subset in skin lesions of psoriasis which recognizes cell-wall extract isolated from group A streptococci (GAS). As a first step in the identification of the streptococcal proteins involved, dermal T-cell lines (TCL) cultured from the lesional skin of 12 human leucocyte antigen (HLA)-typed psoriasis patients were stimulated with GAS cell-wall extract and 14 fractions (MWt approximately 20–100 kDa) separated from the cell-wall extract by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and electroelution, stained for intracellular interferon-γ(IFN-γ) expression and analysed by flow cytometry. All the TCL responded to GAS cell-wall extract to varying extents (3.5–27.6% IFN-γ+). This response was consistently directed against 20–50 kDa cell-wall fractions and inhibited by anti-HLA-DR antibody. TCL with higher responses to GAS cell-wall extract recognized a larger number of fractions within this range than the lower responder TCL. No difference between the level and pattern of response to the fractions was observed for TCL from HLA-DR7+ (n = 6) and HLA-DR7– (n = 6) individuals. This preliminary study has shown a selective response to lower MWt proteins expressed on GAS cell wall by skin Th-1 cells in psoriasis. Further studies are required to identify the proteins involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3083.2003.01309.x
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  • 4
    Electronic Resource
    Electronic Resource
    Genetic diversity among the T-protein genes of group A streptococci (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 5 (1991), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: T protein is a trypsin- and pepsin-resistant molecule on the surface of group A streptococci used as a serological tool to differentiate streptococci of this group. The purpose of this study was to determine the relatedness among the T protein genes of the 25 known T serotypes. DNA probes were constructed which represented various regions of the structural gene for the T6 protein, tee6. The probes were assayed for their ability to hybridize Hin dlll digests of chromosomal DNA from the 25 different T serotypes. Probe pTEE6.3, coding for the entire T6 protein, and pTEE61–299, coding for the amino-terminal half of T6, displayed the highest amount of homology, each binding to 10 of 25 T serotypes. Probes coding for sequences in the carboxy-terminal half of T6 showed considerably less homology among T serotypes with one probe hybridizing with only three out of 25. A synthetic oligonucleotide coding for the carboxy-terminal hydrophobic domain of T6, an area conserved to some degree among several bacterial surface proteins, showed homology with only seven out of 25 T serotypes. Hybridization with sequences outside the tee6 coding area provided additional information on the relatedness of certain sets of T serotypes according to restriction-fragment size heterogeneity. Clearly, there is considerable diversity among T-serotype genes. The data suggest that two or more families of structurally variant T proteins exist, which share only the property of proteolytic resistance and/or, perhaps, some biological function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1991.tb01854.x
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  • 5
    Electronic Resource
    Electronic Resource
    Serial studies on the cellular immune response to streptococcal antigens in acute and convalescent rheumatic fever patients in Trinidad (1986)
    Springer
    Journal of clinical immunology 6 (1986), S. 433-441 
    Details
    ISSN: 1573-2592
    Keywords: Rheumatic fever ; lymphocyte sensitization ; cross-reactive antigens ; group A streptococci
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Acute rheumatic fever (ARF) has the characteristics of an autoimmune disease, triggered by cross-reactive antigens shared by the group A streptococcus and a variety of tissues including the heart, endothelium, and basal ganglia. Using two parameters of cellular reactivity, migration inhibition and blastogenic transformation, ARF patients from Trinidad show significant lymphocyte reactivity to streptococcal antigens, particularly those from an ARF associated streptococcal strain. This reactivity, studied over a 2-year period, peaked at 1 to 6 months after the acute onset and remained significantly elevated for at least 2 years. The reactivity is directed mainly toward a nonionic detergent extractable material in the cell membrane. These studies suggest a possible streptococcal strain specificity in ARF and demonstrate persistent sensitization, which explains the increased susceptibility to recurrences in the 2 years following the acute episode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00915249
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