Saccharomyces cerevisiae cells harboring the gene encoding sarcotoxin IA secrete a peptide that is toxic to plant pathogenic bacteria

Sarcotoxin IA is a cecropin-type antibacterial protein produced by the fles h fly, Sarcophaga peregrina, Similar to other bactericidal small proteins p roduced by insects, sarcotoxin IA is released into the hemolymph of larvae and nymphs upon mechanical injury or bacterial infection. The gene (sarco) that encodes this toxin was introduced into Saccharomyces cerevisiae yeast cells and was expressed under a constitutive yeast promoter. The transforme d yeast cells were grown in a liquid medium, and a peptide with a similar m olecular size to that of the mature sarcotoxin IA was detected in the mediu m by Western blot analysis. The secreted sarcotoxin-like peptide (SLP) had a potent cytotoxic effect against several bacteria, including plant pathoge nic bacteria, similar to the toxic effects of the authentic sareotoxin Ik E rwinia carotovora was more susceptible to the toxic medium than Pseudomonas solanacearum and Pseudomonas syringae pv. lachrymans. Thus, yeast may be u sed in the production of such proteins for employment against various bacte rial pathogens. (C) 1999 Academic Press.