Identification of the Cellular Receptor of Clostridium spiroforme Toxin

Abstract

ABSTRACTClostridium spiroformeproduces the binary actin-ADP-ribosylating toxin CST (C. spiroformetoxin), which has been proposed to be responsible for diarrhea, enterocolitis, and eventually death, especially in rabbits. Here we report on the recombinant production of the enzyme component (CSTa) and the binding component (CSTb) ofC. spiroformetoxin inBacillus megaterium. By using the recombinant toxin components, we show that CST enters target cells via the lipolysis-stimulated lipoprotein receptor (LSR), which has been recently identified as the host cell receptor of the binary toxinsClostridium difficiletransferase (CDT) andClostridium perfringensiota toxin. Microscopic studies revealed that CST, but not the relatedClostridium botulinumC2 toxin, colocalized with LSR during toxin uptake and traffic to endosomal compartments. Our findings indicate that CST shares LSR withC. difficileCDT andC. perfringensiota toxin as a host cell surface receptor.