THE EFFECT OF THIOL-ACTIVE COMPOUNDS AND STEROLS ON THE MEMBRANE-ASSOCIATED HEMOLYSIN OF MYCOPLASMA-PULMONIS

Previous studies had shown that Mycoplasma pulmonis contained a bovine serum albumin-dependent, membrane-associated hemolysin. Biochemical a nalyses were performed to further characterize this activity. The memb rane-associated hemolytic activity could be activated by dithiothreito l and beta-mercaptoethanol, and inactivated by oxidizing compounds, a sulfhydryl inhibitor and heat treatment. Cholesterol and other sterols were inhibitory in a stereo-specific manner, but they did not interfe re with adherence of M. pulmonis to red blood cells. These results ind icated that once attached, the M. pulmonis hemolysin recognized choles terol in the opposing membrane leading to red cell lysis. Because of t he unique location of this toxin and its sensitivity to cholesterol, t he mycoplasma membrane hemolysins may belong to a unique class of bact erial toxins.