ELEVATED EXPRESSION OF CHITINASE-1 AND CHITIN SYNTHESIS IN MYOSIN-II DEFICIENT SACCHAROMYCES-CEREVISIAE

To determine if the attached cells formed in Myosin II-deficient Sacch aromyces cerevisiae result from deficient chitinase 1 (CTS1) expressio n, the activity of chitinase 1 was assayed. Secretion of this enzyme w as not prevented by a MYO1 gene deficiency, and soluble and cell wall- associated Cts1p activity were increased approximately 5-fold and 20-f old, respectively, in these cells. The increase in soluble activity wa s correlated with an increase in enzyme levels. Likewise, intracellula r chitinase activity was increased approximately 22-fold, and the chit in content of cell walls was elevated 2-fold. These data suggest that the origin of myo1-associated phenotypes is not due to deficient chiti nase expression and may instead be due to a deregulation of cell wall metabolism in these cells.