Mutation of TRS130, which encodes a component of the TRAPP II complex, activates transcription of OCH1 in Saccharomyces cerevisiae.

The Saccharomyces cerevisiae Och1p is required for the initiation of the mannose outer chain elongation of cell wall mannoproteins. A trs130(ts1) mutant that showed an elevated expression of the OCH1-reporters was isolated in our laboratory. In this study, we attempted to gain an understanding of the relationship between the defect in the Trs130p function and the elevated expression of OCH1. The trs130(ts1) mutant showed calcofluor white-resistant and hygromycin B-sensitive phenotypes, indicating that the mutant is defective in cell wall integrity. YPT31 and YPT32, the multi-copy suppressors of the trs130(ts1) mutant, differed in the extent of suppression of the mutant phenotypes and in their genetic interaction with TRS130. Our results suggest that the blocking of vesicle transport by a loss of the Trs130p function causes some defect in the cell wall mannoproteins, which leads to the elevated expression of OCH1 through the Skn7p function, to compensate for the defect.