Sphingomyelin-cholesterol synergy facilitates conformational maturation of the cytolysin A pore.

SM–cholesterol synergy lowers the energetic barrier for ClyA conformational maturation by selectively enabling unfolding of the membrane-bound β-tongue motif, yielding a reactive molten-globule intermediate.

• Why it matters: Membrane insertion by pore-forming toxins is a major structural transition, and the field lacks a clear mechanism for how host lipids catalyze the key maturation step.
• What they did: Using vesicle and suspended-lipid-bilayer assays, molecular dynamics, cell permeabilization, and biophysical measurements, the study shows SM–CHOL synergy drives β-tongue unfolding and refolding into the α-helical pore-competent state.
• The result: Conserved lysines K175 and K206 act as cationic anchors; anchor mutants uncouple binding from maturation, and toxin assembly remodels membranes by dismantling liquid-ordered domains.

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