85-2066-60　［取扱停止］Listeriolysin O, PEST-free, Recombinant (LLO) 10ug　209068

特徴

• Listeriolysin O (aka LLO) is a hemolysin produced by Listeria monocytogenes bacteria, the pathogen responsible for causing listeriosis. The toxin may be regarded as a virulence factor, since it is crucial for the virulence of L. monocytogenes. LLO is a single polypeptide protein encoded by the hlyA gene and composed of 529 residues. LLO is a thiol-activated cholesterol-dependent pore forming toxin protein; therefore, it is activated by reducing agents and inhibited by oxidizing agents. Still, LLO differs from other thiol- activated toxins, as its cytolytic activity is maximized at a pH of 5.5. Inside the acidic phagosomes (average pH ~5.9) of cells that have phagocytosed L. monocytogenes, LLO is selectively activated by maximizing activity at a pH of 5.5. Following the phagosome lysis by LLO, the bacterium breaks out into the cytosol, where it is able to grow intracellularly, and the toxin has reduced activity in the more basic cytosol. Thus, LLO permits L. monocytogenes to break out from the phagosomes into the cytosol without harming the plasma membrane of the infected cell, which allows the bacteria to live intracellularly, where they are sheltered from extracellular immune system factors such as the complement system and antibodies. LLO also brings about dephosphorylation of histone H3 and deacetylation of histone H4 in the early phases of infection, before entry of L. monocytogenes into the host cell. The pore-forming activity is not implicated in causing the histone modifications. The modifications of the histones affect the down regulation of genes encoding proteins involved in the inflammatory response. Therefore, LLO may be significant in subverting the host immune response to L. monocytogenes. At its NH2-terminus it possesses a 25 residues long typical signal sequence excited during the secretion process. Moreover, in its NH2-terminus there is also a 19aa PEST-like sequence that may target this toxin for degradation. The PEST-like sequence found in LLO and is considered crucial for virulence, given that mutants lacking the sequence lysed the host cell. Nevertheless, contrary to PEST's supposed role in protein degradation, evidence implies that the PEST-like sequence may control LLO production in the cytosol rather than increase degradation of LLO. Listeriolysin O (LLO) is a single polypeptide protein secreted by the Gram-positive bacterium Listeria monocytogenes. LLO belongs to the group of cholesterol-binding sulfhydrylactivated toxins, the lytic activity of which is enhanced by reducing agents and is suppressed by exposure to oxygen or cholesterol. LLO hemolytic activity is maximum at pH 5.5 and rapidly decreases with the increase of the pH.
• Source:Recombinant protein corresponding to LLO, lacking both the signal secretion sequence and the PEST-like sequence, composed of 471aa starting from aa60-529, with the addition of a methionine in its NH2-terminus, expressed in E. coli.
• Activity:LLO has a hemolytic activity of ~1.25x106HU/mg. 2mM DTT is used to reactivate the toxin.
• Applications:Suitable for use in Cytosolic delivery of molecules, peptides, oligonucleodides and plasmid DNA, production of specific monoclonal antibodies and detection of anti-listeriolysin O antibodies. Other applications not tested.
• Recommended Dilution:Optimal dilutions to be determined by the researcher.
• Storage and Stability:May be stored at 4°C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Aliquots are stable for 12 months. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.