Pichia anomala DBVPG 3003 secretes a ubiquitin-like protein that has antimicrobial activity

The yeast strain Pichia anomala DBVPG 3003 secretes a killer toxin (Pikt) that has antifungal activity
against Brettanomyces/Dekkera sp. yeasts. Pikt interacts with -1,6-glucan, consistent with binding to the cell
wall of sensitive targets. In contrast to that of toxin K1, secreted by Saccharomyces cerevisiae, Pikt killer activity
is not mediated by an increase in membrane permeability. Purification of the toxin yielded a homogeneous
protein of about 8 kDa, which showed a marked similarity to ubiquitin in terms of molecular mass and
N-terminal sequences. Pikt is also specifically recognized by anti-bovine ubiquitin antibodies and, similar to
ubiquitin-like peptides, is not absorbed by DEAE-cellulose. However, Pikt differs from ubiquitin in its sensitivity
to proteolytic enzymes. Therefore, Pikt appears to be a novel ubiquitin-like peptide that has killer activity.