Thiol-independent activity of a cholesterol-binding enterohemolysin (EHly) produced by enteropatogenic ESCherichia coli

FIGUEIRÊDO, P.M.S., SALVADORI, M.R., FURUMURA, M.T., CATANI, C.F., YANO, T.

Departamento de Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP, Brasil.

Enterohemolysin (EHly) produced by Escherichia coli associated with infant diarrhea, showed similar characteristics to those of thiol-activated hemolysins produced by Gram positive bacteria including inactivation by cholesterol, lytic activity towards eukaryotic cells and chemical instability. In this work, we describe the partial purification of EHly by size exclusion chromatography and show that it shares several properties with thiol-activated hemolysins (TAH). TAH have the following general characteristics, in addition to their inactivation by cholesterol: inactivation by oxidation and reactivation with reducing agents, lethality in mice and lytic activity towards eukaryotic cells through the formation of pores in the cell membrane. However, the activity of EHly was not inactivated by oxidation or by SH group blocking reagents and the hemolysin was not lethal to mice. These results suggest that E. coli EHly is not a thiol-activated hemolysin, despite its ability to bind cholesterol.

CORRESPONDENCE TO:

Marcia Regina Salvadori, Rua: Albuquerque Lins, 480, Salto, SP, CEP: 13320-340, Brasil, Email: mrsalvadori@yahoo.com.br