Integration of the Serratia marcescens haemolysin into human erythrocyte membranes
1989; Wiley; Volume: 3; Issue: 3 Linguagem: Inglês
10.1111/j.1365-2958.1989.tb00190.x
ISSN1365-2958
Autores Tópico(s)Venomous Animal Envenomation and Studies
ResumoSummary The haemolytic activity of Serratia marcescens is determined by two proteins, ShIA and ShIB. ShIA integrates into the erythrocyte membrane and causes osmotic lysis through channel formation. The conformation of ShIA and its interaction with erythrocyte membranes were studied by determining the cleavage of ShIA by added trypsin. Our results suggest that the conformation of inactive ShIA (from an ShIB − strain) differs from the active ShIA, and that in a hydrophobic environment (detergent or membrane) active ShIA assumes a conformation distinct from that in buffer. Only active haemolysin adsorbed to erythrocytes. ShIA was firmly integrated into the erythrocyte membrane since it was only released under conditions which also dissolved the integral erythrocyte membrane proteins. Moreover, ShIA integrated into ‘ghosts’ remained there and was not haemolytic when incubated with erythrocytes. From the trypsin cleavage pattern obtained with haemolysin and C‐terminally truncated, but still active, haemolysin derivatives integrated into erythrocytes, and sealed and unsealed erythrocyte ‘ghosts’, we conclude that ShiA is preferentially cleaved by trypsin at a few sites but only from the inside of the erythrocyte. Haemolysin in the erythrocyte membrane forms a water‐filled channel and is resistant to trypsin and other proteases.
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