Saccharomyces cerevisiae YCRO17c/CWH43 encodes a putative sensor/transporter protein upstream of the BCK2 branch of the PKC1‐dependent cell wall integrity pathway

Medientyp: E-Artikel
Titel: Saccharomyces cerevisiae YCRO17c/CWH43 encodes a putative sensor/transporter protein upstream of the BCK2 branch of the PKC1‐dependent cell wall integrity pathway
Beteiligte: Martin‐Yken, Helene; Dagkessamanskaia, Adilia; De Groot, Piet; Ram, Arthur; Klis, Frans; François, Jean
Erschienen: Wiley, 2001
Erschienen in: Yeast
Sprache: Englisch
DOI: 10.1002/yea.731
ISSN: 0749-503X; 1097-0061
Schlagwörter: Genetics ; Applied Microbiology and Biotechnology ; Biochemistry ; Bioengineering ; Biotechnology
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Beschreibung: <jats:title>Abstract</jats:title><jats:p>The <jats:italic>Saccharomyces cerevisiae cwh43‐2</jats:italic> mutant, originally isolated for its Calcofluor white hypersensitivity, displays several cell wall defects similar to mutants in the PKC1–MPK1 pathway, including a growth defect and increased release of β‐1,6‐glucan and β‐glucosylated proteins into the growth medium at increased temperatures. The cloning of <jats:italic>CWH43</jats:italic> showed that it corresponds to <jats:italic>YCR017</jats:italic>c and encodes a protein with 14–16 transmembrane segments containing several putative phosphorylation and glycosylation sites. The N‐terminal part of the amino acid sequence of Cwh43p shows 40% similarity with the mammalian FRAG1, a membrane protein that activates the fibroblast growth factor receptor of rat osteosarcoma (FGFR2‐ROS) and with protein sequences of four uncharacterized ORFs from <jats:italic>Caenorhabditis elegans</jats:italic> and one from <jats:italic>Drosophila melanogaster</jats:italic>. The C‐terminus of Cwh43p shows low similarities with a xylose permease of <jats:italic>Bacillus megaterium</jats:italic> and with putative sugar transporter from <jats:italic>D. melanogaster</jats:italic>, and has 52% similarity with a protein sequence from a <jats:italic>Schizosaccharomyces pombe</jats:italic> cDNA. A Cwh43–GFP fusion protein suggested a plasma membrane localization, although localization to the internal structure of the cells could not be excluded, and it concentrates to the bud tip of small budded cells and to the neck of dividing cells. Deletion of <jats:italic>CWH43</jats:italic> resulted in cell wall defects less pronounced than those of the <jats:italic>cwh43‐2</jats:italic> mutant. This allele‐specific phenotype appears to be due to a G–R substitution at position 57 in a highly conserved region of the protein. Genetic analysis places <jats:italic>CWH43</jats:italic> upstream of the <jats:italic>BCK2</jats:italic> branch of the PKC1 signalling pathway, since <jats:italic>cwh43</jats:italic> mutations were synthetic lethal with <jats:italic>pkc1</jats:italic> deletion, whereas the <jats:italic>cwh43</jats:italic> defects could be rescued by overexpression of <jats:italic>BCK2</jats:italic> and not by high‐copy‐number expression of genes encoding downstream proteins of the <jats:italic>PKC1</jats:italic> pathway However, unlike <jats:italic>BCK2</jats:italic>, whose disruption in a <jats:italic>cln3</jats:italic> mutant resulted in growth arrest in G<jats:sub>1</jats:sub>, no growth defect was observed in a double <jats:italic>cwh43 cln3</jats:italic> mutants. Taken together, it is proposed that <jats:italic>CWH43</jats:italic> encodes a protein with putative sensor and transporter domains acting in parallel to the main PKC1‐dependent cell wall integrity pathway, and that this gene has evolved into two distinct genes in higher eukaryotes. Copyright © 2001 John Wiley & Sons, Ltd.</jats:p>
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