Analysis of Sec 19-1 mutant of Saccharomyces cerevisiae.

Saccharomyces cerevisiae Sec 19-1 cells are secretion mutants defective at 37 degrees C. The cells were analysed in order to ascertain the effect of mutation temperature on cell wall formation. At the restrictive temperature of 37 degrees C, the Sec 19-1 mutants had 37 micrograms/mg N-acetylglucosamine in the wall cells, while the wild type S. cerevisiae showed 84 micrograms/mg hexosamine. The mutants Sec 19-1 showed a maximum activity of chitin synthetase of 0.113 nmoles/min/ml, and the activity increased to 0.33 nmoles/min/ml in the wild type cells. On the other hand, variations of chitin distribution in the wall cells occurred at the restrictive temperature, but changes in actin organization were not evident. The results indicated that the mutation caused variations in the levels of N-acetylglucosamine and chitin synthetase, as well as in cell wall chitin distribution.