Sequence of the preprotoxin dsRNA gene of type I killer yeast: multiple processing events produce a two-component toxin

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Department of Molecular Genetics and Microbiology; Department of Microbiology and Physiological Systems

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Microbiology | Physiology


The preprotoxin gene of the 1.9 kb M1 dsRNA genome from type I killer yeast has been sequenced employing a partial-length cDNA derived from an in vivo transcript. A single open reading frame, commencing with AUG at M1 dsRNA bases 14-16, terminates with UAG at 963-965 and codes for a 316 amino acid protein, believed to be identical to the 34 kd preprotoxin species, M1-P1, synthesized by in vitro translation of denatured M1 dsRNA. N-terminal sequencing of M1-P1 confirms this prediction. Secreted toxin is shown to consist of two dissimilar, disulfide-bonded subunits, alpha and beta, of apparent size 9.5 and 9.0 kd, respectively, whose N-terminal sequences are also found in the predicted preprotoxin sequence. Its proposed domains consist of delta, a 44 amino acid N-terminal segment, followed by alpha and beta, which are separated by gamma, a large central glycosylated segment. Processing sites, domain functions, and the potential role of gamma in immunity are discussed.

DOI of Published Version



Cell. 1984 Mar;36(3):741-51.

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