Ribotoxins are a more widespread group of proteins within the filamentous fungi than previously believed

Abstract

a-Sarcin, restrictocin and mitogillin are the best known members of the family of fungal ribotoxins. In recent years, new members of this family have been discovered and characterised. In this work, we study the occurrence of ribotoxins among di erent species of fungi. The presence of ribotoxins has been identi®ed in some new species by means of genetic studies, as well as expression and activity assays. The ribotoxin genes have been partially sequenced, and demonstrate a high degree of similarity. These studies demonstrate that these toxins are more widespread than previously considered. This is surprising, considering the ribotoxins are such speci®c and potent toxins, of unknown biological function. These studies con®rm the hypothesis that these proteins are naturally engineered toxins derived from ribonucleases of broad substrate speci®city.