NEW POTENTIAL CELL-WALL GLUCANASES OF SACCHAROMYCES-CEREVISIAE AND THEIR INVOLVEMENT IN MATING

Biotinylation of intact Saccharomyces cerevisiae cells with a nonperme ant reagent (Sulfo-NHS-LC-Biotin) allowed the identification of, seven cell wall proteins that were released from intact cells by dithiothre itol (DTT), By N-terminal sequencing, three of these proteins were ide ntified as the known proteins beta-exoglucanase 1 (Exg1p), beta-endogl ucanase (Bgl2p), and chitinase (Cts1p), One protein was related to the PIR protein family, whereas the remaining three (Scw3p, Scw4p, and Sc w10p [for soluble cell wall proteins]) were found to be related to glu canases, Single knockouts of these three potential glucanases did not result in dramatic phenotypes, The double knockout of SCW4 and the hom ologous gene SCW10 resulted in slower growth, significantly increased release of proteins from intact cells by DTT, and highly decreased mat ing efficiency when these two genes were disrupted in both mating type s, The synergistic behavior of the disruption of SCW4 and SCW10 was pa rtly antagonized by the disruption of BGL2. The data are discussed in terms of a possible counterplay of transglucosidase and glucosidase ac tivities.