Further characterization of Mycobacterium ulcerans toxin

Abstract

Mycobacterium ulcerans produces an exotoxin in culture which, when inoculated into guinea pig skin, causes inflammation, necrosis, edema, and other histopathological changes resembling those in infections of humans. The toxin was resistant to heat and to alkalies and was moderately acid labile. Toxic activity was destroyed by Pronase, phospholipase, lipase, amylase, and glucosidase but not by trypsin, collagenase, cellulase, lysozyme, hyaluronidase, or neuraminidase. Toxic activity was resistant to treatment with 2-mercaptoethanol, urea, guanidine hydrochloride, p-chloromercuribenzoate, ethylenediaminetetraacetate, and sodium deoxycholate but was destroyed by sodium m-periodate and sodium dodecyl sulfate. The toxin was precipitated by a wide range of ammonium sulfate concentrations. Extraction with chloroform-methanol or petroleum ether destroyed its activity. Isopycnic density gradient ultracentrifugation in KBr produced a highdensity lipoprotein layer with a 24-fold increase in specific activity. The results indicate that this toxin is a high-molecular-weight phospholipoprotein-polysaccharide complex.

Partial Purification and Characterization of Biological Effects of a Lipid Toxin Produced byMycobacterium ulcerans

“…Cytopathic activity of M. ulcerans toxin is protease resistant and heat stable. Previous literature reported that the toxin was a phospholipoprotein-polysaccharide complex (21). To further ascertain the importance of a protein component, we examined whether exposure of the SF to chymotrypsin and proteinase K resulted in a decrease in cytopathic activity.…”

“…Several papers published in the 1970s described attempts at defining the biochemical properties of this toxin (21,24,36). Investigations by Krieg et al describe the toxin as a heat-stable substance present in the SF, cytoplasmic fraction, and particulate fraction but absent from the cell wall (24).…”

“…Investigations by Krieg et al describe the toxin as a heat-stable substance present in the SF, cytoplasmic fraction, and particulate fraction but absent from the cell wall (24). Further work from this same laboratory concluded that the toxin was composed of "a high-molecular-weight phospholipoprotein-polysaccharide complex" (21).…”

Mycobacterium Ulcerans

“…officers, who remembered the smell of wards full of septic wounds in 1914-18.-Carrod LP: Alexander Fleming: A dedication on the 50th anniversary olthe discovery of penicillin. Br I Fxp Pathol 60: 2, 1979…”

High Rates of Apoptosis in Human Mycobacterium Ulcerans Culture-Positive Buruli Ulcer Skin Lesions

“…For Buruli ulcer, the third most common mycobacterial infection in humans, earlier work described a lipid-like toxin in cell-free culture filtrates of M. ulcerans that is cytotoxic and, upon skin inoculation, causes lesions in laboratory animals similar to human infections. [5][6][7] More recently, a growing body of evidence suggests that an important mechanism by which M. ulcerans causes massive tissue destruction with a disproportionate lack of acute inflammation, unlike M. tuberculosis and M. leprae, is toxin-mediated apoptosis. 2,[8][9][10][11] George and others isolated a compound from M. ulcerans known as mycolactone, a polyketide-derived macrolide that is highly cytotoxic, which causes apoptosis in cell monolayers in vitro and human-like features of Buruli ulcer in guinea pig models.…”