Site of Action of Plague Murine Toxin

Investigations on the mechanism of action of plague murine toxin have revealed that the toxin is capable of inhibiting the respiration of mitochondria isolated from toxin susceptible animals by completing with a non-enzymatic protein, reported to be located in the membranes of mitochondria and to satisfy various criteria for a structural protein, and thereby altering the structural configuration of the multienzymatic unit of a mitochondrion. Studies on the effect of plague murine toxin on protein biosynthesis have shown that Toxin B, one of the two protein components of the plague toxin, inhibits the incorporation of C14 leucine or C14 phenylalanine in the presence of poly U into trichloracetic acid precipitable material by cell-free rat liver systems. This inhibitory effect can be observed with as little as 10 microgram of toxin. The longer Toxin B is preincubated with the supernatant fraction, the greater is the percentage inhibition. Prepared in cooperation with Georgia Univ., Athens. Dept. of Medical Microbiology.