Recombinant murine toxin from Yersinia pestis shows high toxicity and β-adrenergic blocking activity in mice.

Yersinia pestis murine toxin (Ymt) encoded on pMT1 is a 61-kDa protein, a member of the phospholipase D superfamily, which is found in all the domains of life. It is considered to be an intracellular protein required for the survival of Y. pestis in the midgut of the flea, but the exact role of Ymt in the pathogenesis of Y. pestis has not been clarified. Purified Ymt is highly toxic to mice and rats, but the exact mechanism of the animals' death is unclear. Here, we prepared a recombinant Ymt in Escherichia coli BL21 cells, and determined its toxicity and activity. We demonstrated that recombinant Ymt was as toxic to mice as the native protein when administered via the intraperitoneal or intravenous route, and inhibited the elevation of blood sugar caused by adrenaline. We also demonstrated that recombinant Ymt was highly toxic to mice when administered via the muscular or subcutaneous route. We also show that the multiple organ congestion or hemorrhage caused by Ymt poisoning may explain the death of the mice.