The contribution of the O-glycosylated protein Pir2p/Hsp150 to the construction of the yeast cell wall in wild-type cells and beta 1,6-glucan-deficient mutants.
The cell wall of yeast contains a major structural unit, consisting of a cell wall protein (CWP) attached via a glycosylphosphatidylinositol (GPI)-derived structure to beta 1,6-glucan, which is linked in turn to beta 1, 3-glucan. When isolated cells walls were digested with beta 1,6-glucanase, 16% of all CWPs remained insoluble, suggesting an alternative linkage between CWPs and structural cell wall components that does not involve beta 1,6-glucan. The beta 1,6-glucanase-resistant protein fraction contained the recently identified GPI-lacking, O-glycosylated Pir-CWPs, including Pir2p/Hsp150. Evidence is presented that Pir2p/Hsp150 is attached to beta 1,3-glucan through an alkali-sensitive linkage, without beta 1,6-glucan as an interconnecting moiety. In beta 1,6-glucan-deficient mutants, the beta 1,6-glucanase-resistant protein fraction increased from 16% to over 80%. This was accompanied by increased incorporation of Pir2p/Hsp150. It is argued that this is part of a more general compensatory mechanism in response to cell wall weakening caused by low levels of beta 1,6-glucan.
Kapteyn
J C
JC
Center for Fungal Cell Wall Research, University of Amsterdam, The Netherlands. kapteyn@bio.uva.nl
Van Egmond
P
P
Sievi
E
E
Van Den Ende
H
H
Makarow
M
M
Klis
F M
FM
D000468:Alkalies / Q000494:pharmacology; D015152:Blotting, Northern; D015153:Blotting, Western; D002473:Cell Wall / Q000502:physiology; D002686:Chitin / Q000378:metabolism; D005936:Glucans / Q000235:genetics / Q000378:metabolism*; D005964:Glucosyltransferases; D006023:Glycoproteins; D006031:Glycosylation; D006360:Heat-Shock Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D008957:Models, Genetic; D016296:Mutagenesis; D012333:RNA, Messenger / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D047071:beta-Glucans
D000468:Alkalies; D005936:Glucans; D006023:Glycoproteins; C074229:HSP150 protein, S cerevisiae; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D047071:beta-Glucans; D002686:Chitin; C064197:beta-1,6-glucan; D005964:Glucosyltransferases; C095724:GSC2 protein, S cerevisiae