INTRINSIC TOXIN DERIVED PEPTIDE INHIBITS E. COLI ALPHA HEMOLYSIN HEMOLYTIC ACTIVITY

LUCÍA CANÉ; FANNY GUZMÁN; MARÍA ANTONIETA DAZA-MILLONE; SABINA MATÉ; VANESA HERLAX

Congreso; L Reunión Anual de Sociedad Argentina de biofisica; 2022

Alpha hemolysin (HlyA), a toxin secreted by E. coli, presents hemolytic activity which is enhanced by cholesterol, and several CRAC domains (Cholesterol Recognition/interaction Aminoacid Consensus sequence) were found in its sequence. In the present work we studied the interaction with membranes of a peptide, which sequence corresponds to a CRAC region situated between the acylated sites. Specifically, we studied the interaction of the peptide with membranes of different lipid composition by Langmuir monolayer and Surface Plasmon Resonance (SPR). We also tested its lytic and subliytic activity on human erythrocytes, and its capacity to inhibit HlyA activity. Results indicate that this peptide insertion and affinity for membranes is enhanced by cholesterol. Whatsmore, the CRAC peptide inhibits the lytic and sublytic activity of the toxin on human erythrocytes. To investigate which step of the hemolytic process was inhibited FRET and Western blot assays were performed. Results indicate that in the presence of the peptide the binding of the toxin decreases almost 40% and oligomerization a 20%. We are tempted to speculate that the peptide blocks HlyA-cholesterol interaction needed for the adoption of a competitive state for toxin oligomerization. These results open new insight in the development of new therapies for E.coli infections.Acknowledgements: ANPCyT PICT 2017-2393