Pneumolysin generates multiple conductance pores in the membrane of nucleated cells

Patch clamping was used to investigate, for the first time, the electrophysiological properties of pores formed by a cholesterol-dependent cytolysin in the membrane of nucleated cells rather than in artificial membranes as previously. Pneumolysin pores in inside-out patches of CHO cell membranes had a broad range of conductance classified into small (<200 pS), medium (>200 pS and <1 nS) and large (>1 nS). A lytic-deficient mutant of pneumolysin (W433F) induced a similar spectrum of channels but there were more small channels than with wild-type (WT) toxin and the number of events was decreased. The WT toxin also induced channels when given to the inside surface of the plasma membrane.