A temperature-sensitive mutation of Coprinus cinereus, hyt1-1, that causes swelling of hyphal tips

Abstract

The TU25 mutant strain of the basidiomycete Coprinus cinereus grows well at 28°C but not at 37°C. Microscopic examination revealed that TU25 exhibited swelling at hyphal apices after a shift-up from 28°C to 37°C. The temperature sensitivity and hyphal swelling co-segregated through meiosis as expected for a single Mendelian factor, designated hyt1 (hyphal tip). Both defects could be suppressed by the presence of osmotic stabilizers in the medium, suggesting that the hyt1 gene product is required for proper cell-wall function. Chemical analysis of the cell walls, however, failed to detect any clear difference in the composition of the cell-wall polysaccharides between the wild-type and TU25. A DNA fragment which complements the hyt1-1 mutation was cloned and sequenced. The predicted protein in the ORF essential for complementation of hyt1-1 is a novel protein.