Anthrax toxin consists of three proteins secreted by Bacillus anthracis - protective antigen (PA), edema factor (EF) and lethal factor (LF). LF is a Zn2+dependent metalloprotease that cleaves members of the mitogen-activated protein kinase (MAPKK) family, blocking the MARK signaling pathway in professional phagocytes. The binary complex of PA and LF alone, termed lethal toxin or LeTx, is sufficient to induce death of target cells and kill experimental animals, manifesting the symptoms associated with anthrax. As one of the primary virulence factors in the pathogenesis of anthrax, LF has become an important therapeutic target for drug development. A number of small-molecule-based inhibitors of LF have been shown to be able to neutralize cytotoxicity of LeTx in cell cultures and lethality of LeTx in animal trials, promising potential therapeutic value in the treatment of anthrax infection. Human neutrophil a-defensins (HNPs) are members of a growing family of small cationic antimicrobial peptides that kill a broad range of microbes such as bacteria, fungi and viruses, playing an important role in the innate immune defense against infectious pathogens. Kaufmann and colleagues recently discovered that HNP1 non-competitively inhibits LF, preventing cleavage of a MAPKK and restoring impaired MAPK signaling in LeTx-treated macrophages (Kim et al., 2005). Further, HNP1 rescued murine macrophages from B. anthracis-induced cytotoxicity, and in vivo treatment with HNP1-3 protected mice against the fatal consequences of LeTx (Kim et al 2005). In a subsequent report, Mayer-Scholl et al. (2005) demonstrated that B. anthracis spores engulfed by human neutrophils and germinated intracellularly can be effectively killed by HNPs. These findings raise the possibility that a-defensins may be developed as a novel class of antitoxins to combat anthrax infection. Despite the therapeutic potential of a-defensin-based antitoxins for anthrax treatment, the molecular basis for the inhibition of LF by a-defensins remains poorly understood. In this proposal, we seek to decipher the sequence rules and structural determinants that dictate the inhibition of LF by a-defensins, and to design second-generation defensin molecules with significantly improved inhibitory activity. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
7R01AI072732-02
Application #
7557627
Study Section
Drug Discovery and Mechanisms of Antimicrobial Resistance Study Section (DDR)
Program Officer
Xu, Zuoyu
Project Start
2006-12-15
Project End
2011-11-30
Budget Start
2007-07-01
Budget End
2007-11-30
Support Year
2
Fiscal Year
2007
Total Cost
$284,470
Indirect Cost
Name
University of Maryland Baltimore
Department
Type
Organized Research Units
DUNS #
188435911
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Prantner, Daniel; Shirey, Kari Ann; Lai, Wendy et al. (2017) The ?-defensin retrocyclin 101 inhibits TLR4- and TLR2-dependent signaling and protects mice against influenza infection. J Leukoc Biol 102:1103-1113
Kudryashova, Elena; Koneru, Pratibha C; Kvaratskhelia, Mamuka et al. (2016) Thermodynamic instability of viral proteins is a pathogen-associated molecular pattern targeted by human defensins. Sci Rep 6:32499
Kudryashova, Elena; Seveau, Stephanie; Lu, Wuyuan et al. (2015) Retrocyclins neutralize bacterial toxins by potentiating their unfolding. Biochem J 467:311-20
Basta, Daniele; Latinovic, Olga; Lafferty, Mark K et al. (2015) Angiogenic, lymphangiogenic and adipogenic effects of HIV-1 matrix protein p17. Pathog Dis 73:ftv062
Li, Jing; Lehmann, Clara; Chen, Xishan et al. (2015) Total chemical synthesis of human interferon alpha-2b via native chemical ligation. J Pept Sci 21:554-60
Tenge, Victoria R; Gounder, Anshu P; Wiens, Mayim E et al. (2014) Delineation of interfaces on human alpha-defensins critical for human adenovirus and human papillomavirus inhibition. PLoS Pathog 10:e1004360
Kudryashova, Elena; Quintyn, Royston; Seveau, Stephanie et al. (2014) Human defensins facilitate local unfolding of thermodynamically unstable regions of bacterial protein toxins. Immunity 41:709-21
Mastroianni, Jennifer R; Lu, Wuyuan; Selsted, Michael E et al. (2014) Differential Susceptibility of Bacteria to Mouse Paneth Cell ?-Defensins under Anaerobic Conditions. Antibiotics (Basel) 3:493-508
Lu, Wuyuan; de Leeuw, Erik (2014) Functional intersection of Human Defensin 5 with the TNF receptor pathway. FEBS Lett 588:1906-12
Lu, Wuyuan; de Leeuw, Erik (2013) Pro-inflammatory and pro-apoptotic properties of Human Defensin 5. Biochem Biophys Res Commun 436:557-62

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