Bacillus anthracis Lethal Factor Protease Substrate 3 (LFPS3) (Anthrax)

Bacillus anthracis Lethal factor, Protease Substrate 3, AMC derivative MEk2 peptide substrate for high-throughput screening of LF inhibitors (14aa) After inhalation by mammals, Bacillus anthracis spores germinate in alveolar macrophages then migrate to lymph nodes where they multiply. The vegetative bacteria excrete the tripartite exotoxin which consists of three polypeptides: protective antigen (PA, 83kD), lethal factor (LF, 90kD) and oedma factor (OF, 89kD). The two components (OF and LF) of the toxin enzymatically modify substrates within the cytosol of the mammalian cells: The OF is an adenylate cyclase that impairs the host defenses through a variety of mechanisms inhibiting phagocytosis. The LF is a zinc dependent protease that cleaves several mitogen activated protein kinase kinases (MAPKK) and causes lysis of macrophages. To intoxicate mammalian cells, the third component of the toxin PA, binds to a ubiquitously expressed cellular receptor, Tumor Endothelium Marker-8 (TEM8). Upon binding to TEM8, PA is cleaved into 20 and 63kDa fragments (PA20 and PA63) by furin or furin-like proteases. PA20 dissociates into medium and allows the PA63 fragment to heptamerize and bind LF and OF of the toxin. The resulting complex of PA63 fragment with EF and/or OF binds to PA-receptor TEM8/ATR and internalized into endosomes followed by translocation of LF and OF into cytosol of the cells. Anthrax lethal toxin produced by the bacterium Bacillus anthracis is the major cause of death in animals infected with anthrax.One component of this toxin, lethal factor (LF), inactivates membersof the mitogen-activated protein kinase kinase or MEK family throughproteolysis of their NH2 termini. Although LF has been shown to cleave the NH2 termini of select members of the mitogen-activated protein kinase kinase or MEKfamily, the substrate requirements that determine LF specificityare unknown. Indirect evidence suggests that epitopes distal to the cleavage site are required for LF-MEK interaction. B. anthracis Lethal Factor (LF) is comprised of four domains: domain I binds the protective antigen to enter the target cell, domain II, III and IV create a long groove to hold and cleave the MAPKK proteins heptamer to insert into the membrane and form a water filled channel. Source of Peptide An N-acetylated, C-7-amido-4-methylcoumarin (AMC) derivative of a 14-mer peptide substrate designed from the MEK-2 template that is useful for measuring Anthrax lethal factor (LF) metalloproteolytic activity with a detection limit of ~5-10 pM. Reported to be useful for high-throughput screening of LF inhibitors. Sequence (linear): Ac-Gly-Tyr-bAla-Arg-Arg-Arg-Arg-Arg-Arg-Arg-Arg-Val-Leu-Arg-AMC Solubility: DMSO Storage and Stability: Lyophilized powder may be stored at 4 degrees C for short-term only. Stable for 12 months at -20 degrees C. Reconstitute to nominal volume (see reconstitution instructions for peptides) and store at -20 degrees C. For maximum recovery of product, centrifuge the original vial prior to removing the cap. Further dilutions can be made in assay buffer.