Chitinase and chitin synthase 1: counterbalancing activities in cell separation of Saccharomyces cerevisiae.
Previous results [E. Cabib, A. Sburlati, B. Bowers & S. J. Silverman (1989) Journal of Cell Biology 108, 1665-1672] strongly suggested that the lysis observed in daughter cells of Saccharomyces cerevisiae defective in chitin synthase 1 (Chs1) was caused by a chitinase that partially degrades the chitin septum in the process of cell separation. Consequently, it was proposed that in wild-type cells, Chs1 acts as a repair enzyme by replenishing chitin during cytokinesis. The chitinase requirement for lysis has been confirmed in two different ways: (a) demethylallosamidin, a more powerful chitinase inhibitor than the previously used allosamidin, is also a much better protector against lysis and (b) disruption of the chitinase gene in chs1 cells eliminates lysis. Reintroduction of a normal chitinase gene, by transformation of those cells with a suitable plasmid, restores lysis. The percentage of lysed cells in strains lacking Chs1 was not increased by elevating the chitinase level with high-copy-number plasmids carrying the hydrolase gene. Furthermore, the degree of lysis varied in different chs1 strains; lysis was abolished in chs1 mutants containing the scs1 suppressor. These results indicate that, in addition to chitinase, lysis requires other gene products that may become limiting.
Cabib
E
E
Laboratory of Biochemistry and Metabolism, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Silverman
S J
SJ
Shaw
J A
JA
D002455:Cell Division; D002687:Chitin Synthase / Q000235:genetics / Q000378:metabolism*; D002688:Chitinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D016153:Genes, Suppressor; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology* / Q000235:genetics
D002687:Chitin Synthase; D002688:Chitinases