Isolation of a gene that is involved in Campylobacter jejuni 81116 cytotoxin activation


  • Editor: George Mendz

Correspondence: Peter J. Coloe, School of Applied Sciences, Building 223 Level 1, Plenty Road, Bundoora, Victoria, Australia. 3083. Tel.: +61 3 99257104; fax: +61 3 99257110; e-mail:


Cytotoxin fractions were isolated from Campylobacter jejuni 81116 and semi-purified by size-exclusion liquid chromatography. The fraction showing the strongest toxicity was injected into mice to produce antiserum. The antiserum was used to screen a C. jejuni 81116 cosmid library. Nine genes were identified in overlapping cosmid inserts that induced reactivity with the antiserum. One of these genes showed high similarity to a periplasmic protein of unknown function and its isogenic mutant showed decreased toxicity compared to the C. jejuni 81116 wild type. This gene contains a Gram-negative bacterial RTX toxin-activating protein C signature, which suggests it may play a role in C. jejuni 81116 cytotoxin activation.