The gene of the budding yeast is required for the arrest of cell proliferation upon nutrient exhaustion: mutants carry on dividing and in the absence of growth become abnormally small. It is reported here that overexpression of Whi2 from the promoter results in filamentous growth - cells fail to complete cytokinesis, the budding pattern changes from axial to polar, cells become elongated and cell size increases threefold. In many ways, these filaments resemble the pseudohyphae which result from nitrogen-limited growth and the filaments seen during the invasive growth of haploids. However, Whi2-induced filament formation is reduced, but not blocked, by mutations in or which do block pseudohypha formation. Furthermore, pseudohypha formation can still occur in a diploid in which both copies of the gene have been deleted. Thus Whi2-induced filament formation and pseudohypha formation must come about through the action of different pathways. Despite this, a mutation in the gene, which is required for pseudohypha formation, does block Whi2-induced filament formation. Concanavalin A pulse-chase experiments show that new cell wall material is incorporated only into the tips of the apical cells. An extragenic suppressor of the allele also results in filamentous growth. These results suggest that Whi2 negatively regulates a function required for the budding mode of cell proliferation including cytokinesis. This function is defined wholly or in part by the allele.


Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error