In silicio identification of glycosyl-phosphatidylinositol-anchored plasma-membrane and cell wall proteins ofSaccharomyces cerevisiae

Abstract

Use of the Von Heijne algorithm allowed the identification of 686 open reading frames (ORFs) in the genome of Saccharomyces cerevisiae that encode proteins with a potential N-terminal signal sequence for entering the secretory pathway. On further analysis, 51 of these proteins contain a potential glycosyl-phosphatidylinositol (GPI)attachment signal. Seven additional ORFs were found to belong to this group. Upon examination of the possible GPI-attachment sites, it was found that in yeast the most probable amino acids for GPI-attachment are asparagine and glycine.In yeast, GPI-proteins are found at the cell surface, either attached to the plasma-membrane or as an intrinsic part of the cell wall. It was noted that plasma-membrane GPI-proteins possess a dibasic residue motif just before their predicted GPI-attachment site. Based on this, and on homologies between proteins, families of plasma-membrane and cell wall proteins were assigned, revealing 20 potential plasma-membrane and 38 potential cell wall proteins. For members of three plasma-membrane protein families, a function has been described. On the other hand, most of the cell wall proteins seem to be structural components of the wall, responsive to different growth conditions.The GPI-attachment site of yeast slightly differs from mammalian cells. This might be of use in the development of anti-fungal drugs. 1997 John Wiley & Sons, Ltd.

Genome‐wide identification of fungal GPI proteins

“…The length of the C-terminal signal peptide normally varies between 15 and 30 residues (Udenfriend and Kodukula, 1995) but, as was shown in S. cerevisiae for Gas1, signal peptides of 31 residues do occur (Nuoffer et al, 1991). In the set of S. cerevisiae GPI proteins so obtained, Asn or Gly predominated at the GPI attachment site (Caro et al, 1997).…”

“…At their Ctermini, GPI proteins have a second hydrophobic domain, which is cleaved off and replaced with a GPI anchor, a preformed lipid in the membrane of the endoplasmic reticulum (Orlean, 1997). Two independent studies aimed at genome-wide identification of the GPI proteins of Saccharomyces cerevisiae have earlier shown that sequence motifs can be successfully used to identify most of the GPI proteins (Caro et al, 1997;Hamada et al, 1998a). Hamada and co-workers used three criteria to select for GPI proteins: (a) the presence of a hydrophobic tail; (b) the presence of a N-terminal signal peptide for secretion; and (c) the presence of a serine/threonine (S/T)-rich region.…”

“…Hamada and co-workers used three criteria to select for GPI proteins: (a) the presence of a hydrophobic tail; (b) the presence of a N-terminal signal peptide for secretion; and (c) the presence of a serine/threonine (S/T)-rich region. Although often found in GPI proteins, the presence of a S/T-rich region has not shown to be an absolute prerequisite for GPI proteins to become attached to a GPI-anchor and therefore Caro et al (1997) did not use this feature as a selection criterium. With the first selection criterium being the presence of a N-terminal signal peptide for secretion, final identification of GPI proteins by Caro et al (1997) was based on a more specific definition of the GPI-attachment site (ω-site) and its downstream sequences in the C-terminal region of GPI proteins as described by Udenfriend and Kodukula (1995) and Nuoffer et al (1993).…”

Binding assay for incorporation of alkali‐extractable proteins in the Saccharomyces cerevisiae cell wall

“…Such physiological requirements brought about the evolution of a complex structure composed of β-glucans and mannoproteins, with a small but essential amount of chitin. So far, more than 30 different mannoproteins have been identified in the wall (Cappellaro et al, 1998;Mrša et al, 1997;Yin et al, 2005) and about twice as many were postulated as a result of the S. cerevisiae genome screening (Caro et al, 1997). They can be divided into three groups according to the way they are linked to glucan.…”

Mammalian PIG-L and its yeast homologue Gpi12p are N-acetylglucosaminylphosphatidylinositol de-N-acetylases essential in glycosylphosphatidylinositol biosynthesis

“…GPIanchored proteins are found in yeast [3], mammals [2] and plants [4] but are especially abundant in protozoan parasites [5]. The core structure and the biosynthetic steps of GPI are basically conserved in various organisms [5,6].…”