Submitted to: American Society of Human Genetics
Publication Type: Abstract Only
Publication Acceptance Date: August 2, 1998
Publication Date: N/A
Technical Abstract: Our recent identification and characterization of a trichothecene toxin resistance gene, TRIr, in Fusarium sporotrichioides has led to the functional identification of the yeast open reading frame (ORF) YLL063c (GenBank Z73168 or ORF L0549, GenBank Z47973) located on chromosome XII. The sequence of YLL063c predicts a protein of 474 residues that has 45% identity and 70% similarity to TRIr. TRIr encodes a 3-O-acetyltransferase which converts the primary substrate of isotrichodermal to isotrichodermin, intermediates in the T-2 toxin biosynthetic pathway. TRIr is also capable of utilizing a wide variety of trichothecenes as substrates. Experiments designed to characterize trichothecene metabolism in yeast transformants carrying TRIr, detected low levels of 3-O-acetylation in the untransformed yeast host strain (RW2802). To determine if the product of YLL063c was responsible for this activity, the YLL063c ORF was disrupted in the yeast strain RW2802. Analysis of the YLL063c knock-out strain indicated that YLL063c is not required for growth, therefore, it is considered a nonessential gene. In addition, no trichothecene 3-O-acetylation activity was detected. Based on these results and the structural and functional similarities to TRIr, we propose that YLL063c encodes an acetyltransferase capable of trichothecene 3-O-acetylation and have named this gene Tac1. The primary substrate of Tac1 in yeast is under study.