Difference in cholesterol-binding and cytolytic activities between listeriolysin O and seeligeriolysin O: a possible role of alanine residue in tryptophan-rich undecapeptide

We have constructed recombinant listeriolysin O (rLLO) and seeligeriolysin O (rLSO) from Listeria monocytogenes and Listeria seeligeri, respectively. In hemolysis and cholesterol-binding assays, the specific activity of recom binant toxin was lower for LSO as compared to LLO. To understand the molecu lar basis of this difference, in particular with respect to the conserved T rp-rich undecapeptide, a naturally occurring Ala To Phe substitution in LSO was introduced into rLLO. The rLLO:A488F hemolysin exhibited a reduced act ivity in both hemolysis and cholesterol-binding. The reverse mutation, inse rted into rLSO, also increased the hemolytic activity of this mutant LSO. T hese results suggested that the natural replacement of Ala to Phe is involv ed in the weak cytolytic activity of LSO. (C) 2001 Federation of European M icrobiological Societies. Published by Elsevier Science B.V. All rights res erved.