Lethal factor

Anthrax toxin Lethal factor Lethal factor MEKs Endoprotease Increase in intracellular cAMP Inhibition of MAP-kinase pathways Calmodulin dependent adenylylcyclase... 

The anthrax toxin is a tripartite toxin and consists ofthe binding component protective antigen (PA), the lethal factor (LF), which is a metalloprotease, and the edema factor (EF), which is a calmodulin-dependent adenylyl-cyclase. Both enzyme components are translocated via PA into target cells. PA is activated by furin-induced cleavage and forms heptamers, which are similar to the binding components of C2 toxin and iota toxin. In the low pH compartment of endosomes, the heptamers form pores to allow translocation of LF and EF. LF cleaves six of the seven MEKs (MAPK-kinases) thereby inhibiting these enzymes. The functional consequence is the blockade of the MAPK pathways that control cell proliferation, differentiation, inflammation, stress response, and survival. Whether this is the reason for the LT-induced cell death of macrophages is not clear [1]. 

MA M34 M34.001 Anthrax lethal factor Component of anthrax toxin... 

The recruitment of zinc for a structural role, or to activate an enzyme, has been observed. The zinc ion induces the dimerization of human growth hormone (hGH), with two Zn ions associated per dimer of hGH. This is confirmed by replacement of possible zinc binding residues resulting in weakened binding of the zinc ion. Formation of a zinc-hGH dimeric complex may be important for storage of hGH in secretory granules.975 In a toxic role, anthrax lethal factor is one of the three components of the secreted toxin and is a zinc-dependent protease that cleaves a protein kinase and causes lysis of macrophages.976... 

The anthrax bioterrorist attacks that followed the events of September 11th 2001 resulted in a renewed interest BadUus anthracis, the causative agent of this disease. Research has focused on the development of better vaccines than the one currently available. It has been estimated that the aerosolized release of 100 kg of anthrax spores upwind of Washington DC would cause mortalities of 130,000-3,000,000 [63]. Nonetheless, wild-type Bacillus anthracis is susceptible to conventional antibiotics, including penicillin, oxyfloxacin and ciprofloxacin. The problem lies not with the bacterial infection itself, but with three proteins released by the bacteria - protective antigen (PA, 83 kDa), lethal factor (LF, 90 kDa) and edema factor (EF, 89 kDa) -known as anthrax toxins [63]. 

Control wild type (extract stored for 7 days % Control wild type no lethal factor (LF) (extract stored for 2 days) — — Control wild type no LF (extract stored for 7 days) Control pLD-JWl no LF (extract stored for 2 days) —0— Control pLD-JWl no LF (extract stored for 7 days). 

A Ru-Josiphos catalyst was highly selective for the hydrogenation of an intermediate for an anthrax lethal factor inhibitor with a tetra-substituted C=C bond, as depicted in Figure 37.8 (Merck [44]). Rh-Josiphos (Lonza [42]) and Rh-Bo-Phoz (Eastman [45]) catalysts were effective for the hydrogenation of an exocy-clic and a cyclopropyl-substituted C=C bond. 

Anthrax lethal factor metalloproteinase (Table 1, entry 7) Anthrax lethal factor metalloproteinase is an integral component of the tripartite anthrax lethal toxin and is required for the onset and progression of anthrax. About 300 scaffolds were selected for an NMR-based assay leading to the carboxylic acid fragment 31 [42]. Subsequent synthetic elaboration led to nanomolar inhibitors such as 32. 

Anthrax Anthrax is a toxin with three separate components a protective antigen (PA), an edema factor (EF), and a lethal factor (LF). 

Very recently the protein structures of ACE with the bound inhibitors Lisinopril (Fig. 4) and Captopril were published (101,102). Also the protein structure of the LF from Bacillus anthracis (PDB-Code 1J7N) caused a sensation, which is now available to the public (Fig. 14b) (103). LF is part of the toxic exotoxin complex composed of three distinct proteins (protective antigen PA, the lethal factor LF and the edema factor EF), and is thought to be the most toxic... 

Fig. 14. Active site (a) of the angiotensin converting enzyme (ACE) with Lisinopril inhibitor bound to zinc(II) (PDB-Code 1086) (101), (b) of the lethal factor of Bacillus anthracis (PDB-Code 1J7N) (103).

Recently, a SAMDI-MS assay was described by means of which endogenous caspase protease activities in cell lysates can be determined [26], Similar to the assay used to determine anthrax lethal factor inhibitors, peptide substrate SAMs for either caspase-3 or -8 were treated with cell lysates. In contrast to fluorescence assays, also longer peptide substrates could be used, thus enabling a better resolution of the two caspase activities. 

Min, D.H., Tang, W.J., Mrksich, M. Chemical screening by mass spectrometry to identify inhibitors of anthrax lethal factor. Nat. Biotcchnol. 2004, 22, 717-723. 

Melnyk R.A., Hewitt K.M., Lacy D.B., Lin H.C., Gessner C.R., Li S., Woods V.L. Jr, Collier R.J. Structural determinants for the binding of anthrax lethal factor to oligomeric protective antigen. J. Biol. Chem. 

Anthrax toxin is a bacterial toxin from Bacillus anthracis consisting of three parts protective antigen (PA), lethal factor (LF) and edema factor (EF). Both LF and EF compete for binding sites on the PA protein. The PA protein binds with high affinity to an as yet unknown receptor on macrophages and related cell types. When PA is internalized by the target cells, it functions as a shuttle protein for either EF or LF. Intracellularly, in the acidic environment of the endosome, EF and LF are capable of entering the cytosol by pH-dependent pore formation [139]. 

Other Aminoglycoside Targets The Anthrax Lethal Factor 310... 

Key words Anthrax, Lethal factor, Metalloproteinases, Virtual screening, Docking and scoring,... 

Chiu T, Solberg J, Patil S et al (2009) Identification of novel non-hydroxamate anthrax toxin lethal factor inhibitors by topo-meric searching, docking and scoring, and in vitro screening. J Chem Inf Model 49 2726-2734... 

Chiu TL, Amin EA (2012) Development of a comprehensive, validated pharmacophore hypothesis for anthrax toxin lethal factor (LF) inhibitors using genetic algorithms, Pareto scoring, and structural biology. J Chem Inf Model, 52 1886-1897... 

Chopra AP, Boone S, Liang X et al (2003) Anthrax lethal factor proteolysis and inactivation of MAPK kinase. J Biol Chem 278 9402-9406... 

Vitale G, Bernardi L, Napolitani G et al (2000) Susceptibility of mitogen-activated protein kinase kinase family members to proteolysis by anthrax lethal factor. Biochem J 352 739-745... 

Shoop WL, Xiong Y, Wiltsie J et al (2005) Anthrax lethal factor inhibition. Proc Natl Acad Sci USA 102 7958-7963... 

Panchal RG, Hermone AR, Nguyen TL et al (2004) Identification of small molecule inhibitors of anthrax lethal factor. Nat Struct Mol Biol 11 67-72... 

Yuan H, Johnson SL, Chen LH et al (2010) A novel pharmacophore model for the design of anthrax lethal factor inhibitors. Chem Biol Drug Des 76 263-268... 

Agrawal A, de Oliveira CA, Cheng Y et al (2009) Thioamide hydroxypyrothiones supersede amide hydroxypyrothiones in potency against anthrax lethal factor. J Med Chem 52 1063-1074... 

Roy J, Kumar UC, Machiraju PK et al (2010) In silico studies on anthrax lethal factor inhibitors pharmacophore modeling and virtual screening approaches towards designing of novel inhibitors for a killer. J Mol Graph Model 29 256-265... 

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