The TEA / ATTS transcription factor Y l T ec1p represses the yeast‐to‐hypha transition in the dimorphic yeast Y arrowia lipolytica

Tec1p in the budding yeast S accharomyces cerevisiae is important for dimorphic transition. In this study, we identified a homologue of Tec1p, YlTec1p, in the distantly related dimorphic yeast Y arrowia lipolytica . Y l T ec1p contains an evolutionarily conserved TEA / ATTS DNA ‐binding domain. Expression of Y l TEC 1 in S. cerevisiae tec1 Δ cells rescued the invasive growth defect and activated a FLO11‐lacZ reporter, indicating that Y l T ec1p is functionally related to T ec1p. However, Y l TEC 1 expression failed to activate an FRE‐lacZ reporter, suggesting that these two transcription factors are different. Y l TEC 1 plays a negative role in the yeast‐to‐hypha transition in Y . lipolytica based on gene deletion and overexpression studies. We show that Y l T ec1p activates rather than represses gene expression in Y . lipolytica by yeast one‐hybrid assay, and Y l T ec1p is critical for the activation of FLO11‐lacZ in Y . lipolytica . In addition, Y l T ec1p localized to the nucleus and its nuclear localization decreased during hyphal growth. We speculate that Y l T ec1p may normally regulate the expression of a set of target genes that may prevent rather than promote hyphal development in Y . lipolytica . Our study also suggests that Y l TEC 1 may not be largely regulated by the c AMP –protein kinase A pathway.