Clostridium spiroforme toxin is a binary toxin which ADP-ribosylates cellular actin

Area of Science:

• Microbiology
• Toxicology
• Protein biochemistry

Background:

• Clostridium species are known to produce various toxins.
• Binary toxins, like C. perfringens iota toxin and C. botulinum C2 toxin, consist of two components: an ADP-ribosyltransferase and a translocation/binding moiety.
• The characterization of novel binary toxins is crucial for understanding bacterial pathogenesis.

Purpose of the Study:

• To purify and characterize the toxic components from Clostridium spiroforme strain 246.
• To determine the enzymatic activity and biological effects of the purified components.
• To investigate the relationship of C. spiroforme toxin to other known binary toxins.

Main Methods:

• Purification of heterogeneous protein population (Sa) exhibiting ADP-ribosyl transferase activity from C. spiroforme.
• Separation of a trypsin-activated protein (Sb) from the bacterial supernatant.
• Assay of toxicity in mice and cytotoxicity on Vero cells upon co-administration of Sa and Sb.
• Immunological cross-reactivity analysis of Sa with antibodies against known binary toxin components.

Main Results:

• Purified Sa proteins (43-47 kDa) showed ADP-ribosyl transferase activity.
• Sa alone had no lethal or cytotoxic effects.
• Co-administration of Sa with trypsin-activated Sb resulted in lethal effects in mice and cytotoxicity on Vero cells.
• Sa showed immunological cross-reactivity with the light chain of C. perfringens iota toxin and C. difficile 196 strain ADP-ribosyltransferase, but not with C. botulinum C2 toxin component I.

Conclusions:

• Clostridium spiroforme produces a binary toxin system.
• The ADP-ribosyltransferase component (Sa) of C. spiroforme toxin is functionally and immunologically related to iota toxin.
• C. spiroforme toxin represents a novel binary toxin closely related to iota toxin.