Bacterial pathogens have developed remarkable strategies to usurp host cell processes to establish infection, evade immunity, and disseminate to distal sites in the host. A key highly evolved virulence strategy shared by major human bacterial pathogens is the conscription of components of the host hemostasis system to assist survival of the microorganism against host innate defenses. One important human pathogen, Gram+ Group A Streptococcus pyogenes (GAS), is a model for employing such a tactic. There are >250 surface-expressed M- protein (M-Prt)-based serotypes of GAS that colonize pharyngeal and skin epithelial cells, and which possess the full range of minor-to-severe virulence. Many of these GAS strains contain highly expressed M-Prts, viz., PAM, that directly interact with host human plasminogen (hPg), whereas the M-Prts of some other strains (e.g., M1, M3) first interact with host fibrinogen (hFg), thus enabling the subsequent binding of hPg to the cells. These GAS cells also secrete coevolved subforms of streptokinase (SK) that specifically activate GAS-bound hPg to the serine protease, plasmin (hPm). In this manner, an active plasma inhibitor-resistant protease is generated on GAS that participates via several mechanisms to protect GAS against host innate defenses. The overall goal of this proposal centers on a unique combination of structural and biological studies of the productive interactions that mediate the binding and activation of hPg on M-Prts of GAS cells in vitro, ex vivo, and in vivo. The specific studies proposed to address this overall goal are contained in two Specific Aims, viz., Specific Aim 1. (a) To use biophysical approaches, e.g., SPR, to study the in vitro binding properties of hPg and to specific M-Prts, viz., PAM, as well as individual domains of this protein to minimize the primary sequences needed to provide the high affinity binding of hPg to PAM; (b) to study atomic level binding and dynamics of the PAM/hPg domains by high-resolution NMR and X-ray crystallography; and (c) to correlate the binding data with the activation of hPg on GAS cells containing PAM and variants of this protein to assess the nature of the productive binding of hPg to specific M-Prt domains. Hypothesis: these approaches will allow identification of the essential structural features of PAM that facilitate the binding and activation of hPg on specific types of GAS cells.
Specific Aim 2. To generate and employ partially humanized mouse Pg transgenic mice, as well as transgenic bacteria with deletions of PAM and/or SK, to examine the effects of conscription of the fibrinolytic system on the stages of virulence of PAM-containing GAS. Hypothesis: using the knowledge gained in Aim 1, we will be capable of rationally designing mice and bacteria with altered virulence and identify the stages in which hPm bound to GAS exhibits its greatest effects. PHS Impact: A deepened understanding of the manner in which GAS interacts with the host innate immune system will allow approaches to be developed to attenuate the severity of GAS infections in humans.

Public Health Relevance

Group A streptococcal (GAS) infections affect >700M people annually worldwide, with ~18M of these considered severe, and another ~600K highly invasive types with a fatality rate of ~30%. Among the important virulence strategies employed by GAS is their ability to produce proteins to usurp the host fibrinolytic system in order to assimilate a proteolytic surface on GAS that benefits its dissemination. We propose to study the factors produced by GAS that allow the use of the human fibrinolytic system to generate a bacterial proteolytic surface, thus allowing new therapeutic strategies to be developed to attenuate this group of morbid and often fatal bacterial species.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Hemostasis and Thrombosis Study Section. Committee was terminated on 11/30/2020. (HT)
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Sarkar, Rita
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University of Notre Dame
Schools of Arts and Sciences
Notre Dame
United States
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Flaherty, Rebecca A; Donahue, Deborah L; Carothers, Katelyn E et al. (2018) Neutralization of Streptolysin S-Dependent and Independent Inflammatory Cytokine IL-1? Activity Reduces Pathology During Early Group A Streptococcal Skin Infection. Front Cell Infect Microbiol 8:211
Miles, L A; Baik, N; Bai, H et al. (2018) The plasminogen receptor, Plg-RKT, is essential for mammary lobuloalveolar development and lactation. J Thromb Haemost 16:919-932
Liang, Zhong; Stephens, Melissa; Ploplis, Victoria A et al. (2018) Draft Genome Sequences of Six Skin Isolates of Streptococcus pyogenes. Genome Announc 6:
Urano, T; Castellino, F J; Suzuki, Y (2018) Regulation of plasminogen activation on cell surfaces and fibrin. J Thromb Haemost :
Glinton, Kristofor; Beck, Julia; Liang, Zhong et al. (2017) Variable region in streptococcal M-proteins provides stable binding with host fibrinogen for plasminogen-mediated bacterial invasion. J Biol Chem 292:6775-6785
Yuan, Yue; Zajicek, Jaroslav; Qiu, Cunjia et al. (2017) Conformationally organized lysine isosteres in Streptococcus pyogenes M protein mediate direct high-affinity binding to human plasminogen. J Biol Chem 292:15016-15027
Gupta, Kamlesh K; Donahue, Deborah L; Sandoval-Cooper, Mayra J et al. (2017) Plasminogen Activator Inhibitor-1 Protects Mice Against Cardiac Fibrosis by Inhibiting Urokinase-type Plasminogen Activator-mediated Plasminogen Activation. Sci Rep 7:365
Bao, Yun-Juan; Liang, Zhong; Mayfield, Jeffrey A et al. (2016) Novel genomic rearrangements mediated by multiple genetic elements in Streptococcus pyogenes M23ND confer potential for evolutionary persistence. Microbiology 162:1346-59
Bao, Yun-Juan; Shapiro, B Jesse; Lee, Shaun W et al. (2016) Phenotypic differentiation of Streptococcus pyogenes populations is induced by recombination-driven gene-specific sweeps. Sci Rep 6:36644
Bao, Yun-Juan; Liang, Zhong; Mayfield, Jeffrey A et al. (2016) Genomic Characterization of a Pattern D Streptococcus pyogenes emm53 Isolate Reveals a Genetic Rationale for Invasive Skin Tropicity. J Bacteriol 198:1712-24

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