Biomedical subjects

I Moukadiri

Publications and source records attributed to I Moukadiri.

4 recordsLinked to original sources

PubMed2001

YJL159w does encode Pir2/Hsp150.

In this paper we compare the sequence of the gene HSP150/PIR2, independently determined by two different groups, with that present in the yeast database as YJL159w, determined within the Yeast Sequencing Project. Although YJL159w is believed to encode Hsp150/Pir2, there are important differences between the amino acid sequence coded by this ORF and that of HSP150/PIR2. To find out if this divergence is due to strain polymorphism or to a possible sequencing error, we have analysed the diverging zone of this ORF in three strains and have found it entirely consistent with the sequence reported as HSP150/PIR2, concluding that the divergence is probably due to a sequencing error in YJL159w.

Artifacts↗

PubMed2001

Evidence for the attachment of Hsp150/Pir2 to the cell wall of Saccharomyces cerevisiae through disulfide bridges.

Here we present evidence that Hsp150/Pir2, a member of the Pir family of cell wall proteins, can be extracted from the purified cell walls of Saccharomyces cerevisiae by treatment with beta-mercaptoethanol, demonstrating that at least part of this protein is attached to the cell wall through disulfide bridges. We also present evidence that Pir4, another member of this family, is partly secreted to the growth medium. Finally we propose a hypothesis to explain the relationship between the differently localized forms of particular members of the Pir family of cell wall proteins.

Cell Wall↗

PubMed1999

Identification of two mannoproteins released from cell walls of a Saccharomyces cerevisiae mnn1 mnn9 double mutant by reducing agents.

In this report, we present the identification of the main polypeptides that are extracted from purified cell walls of a Saccharomyces cerevisiae mnn1 mnn9 strain by reducing agents. Treatment of the purified cell walls of this strain with beta-mercaptoethanol releases several mannoproteins, of which three, with apparent sizes of 120, 45, and 40 kDa, are the most abundant. Analysis of the amino-terminal sequences revealed that the 120-kDa mannoprotein is Bar1p, the protease involved in the so-called barrier activity in yeast cells, and that the 45- and 40-kDa mannoproteins are the Kex2-unprocessed and Kex2-processed forms of the gene product of open reading frame (ORF) YJL158c, an ORF that belongs to the PIR (protein with internal repeats) family of genes, composed thus far of PIR1, PIR2/HSP150, and PIR3. Accordingly we have named this gene PIR4, and Pir4 denotes the 40-kDa Kex2-processed form of the mannoprotein. We have characterized Pir4 and have shown the feasibility of using it as a fusion partner for the targeting of recombinant proteins to the cell wall.

Amino Acid Sequence↗

PubMed1997

Identification of a mannoprotein present in the inner layer of the cell wall of Saccharomyces cerevisiae.

Cell wall extracts from the double-mutant mnn1 mnn9 strain were used as the immunogen to obtain a monoclonal antibody (MAb), SAC A6, that recognizes a specific mannoprotein--which we have named Icwp--in the walls of cells of Saccharomyces cerevisiae. Icwp runs as a polydisperse band of over 180 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of Zymolyase extracts of cell walls, although an analysis of the secretory pattern of the mannoprotein shows that at the level of secretory vesicles, it behaves like a discrete band of 140 kDa. Immunofluorescence analysis with the MAb showed that Icwp lies at the inner layer of the cell wall, being accessible to the antibody only after the outer layer of mannoproteins is disturbed by treatment with tunicamycin. The screening of a lambda gt11 expression library enabled us to identify the open reading frame (ORF) coding for Icwp. ICWP (EMBL accession number YLR391w, frame +3) codes for 238 amino acids, of which over 40% are serine or threonine, and contains a putative N-glycosylation site and a putative glycosylphosphatidylinositol attachment signal. Both disruption and overexpression of the ORF caused increased sensitivities to calcofluor white and Congo red, while the disruption caused an increased sensitivity to Zymolyase digestion, suggesting for Icwp a structural role in association with glucan.

Antibodies, Monoclonal↗