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 Saccharomyces cerevisiae result from deficient chitinase 1 (CTS1) expression, the activity of chitinase 1 was assayed. Secretion of this enzyme was not prevented by a MYO1 gene deficiency, and soluble and cell wall-associated Cts1p activity were increased approximately 5-fold and 20-fold, respectively, in these cells. The increase in soluble activity was correlated with an increase in enzyme levels. Likewise, intracellular chitinase activity was increased approximately 22-fold, and the chitin content of cell walls was elevated 2-fold. These data suggest that the origin of myo1-associated phenotypes is not due to deficient chitinase expression and may instead be due to a deregulation of cell wall metabolism in these cells.