title: CAL1, a gene required for activity of chitin synthase 3 in Saccharomyces cerevisiae.
abstract: The CAL1 gene was cloned by complementation of the defect in Calcofluor-resistant calR1 mutants of Saccharomyces cerevisiae. Transformation of the mutants with a plasmid carrying the appropriate insert restored Calcofluor sensitivity, wild-type chitin levels and normal spore maturation. Southern blots using the DNA fragment as a probe showed hybridization to a single locus. Allelic tests indicated that the cloned gene corresponded to the calR1 locus. The DNA insert contains a single open-reading frame encoding a protein of 1,099 amino acids with a molecular mass of 124 kD. The predicted amino acid sequence shows several regions of homology with those of chitin synthases 1 and 2 from S. cerevisiae and chitin synthase 1 from Candida albicans. calR1 mutants have been found to be defective in chitin synthase 3, a trypsin-independent synthase. Transformation of the mutants with a plasmid carrying CAL1 restored chitin synthase 3 activity; however, overexpression of the enzyme was not achieved even with a high copy number plasmid. Since Calcofluor-resistance mutations different from calR1 also result in reduced levels of chitin synthase 3, it is postulated that the products of some of these CAL genes may be limiting for expression of the enzymatic activity. Disruption of the CAL1 gene was not lethal, indicating that chitin synthase 3 is not an essential enzyme for S. cerevisiae.
authors.affiliation: Instituto de Microbiología Bioquímica, Facultad de Biología, Consejo Superior de Investigaciones Científicas, Salamanca, Spain.
authors.forename: M H
authors.initials: MH
authors.lastname: Valdivieso
authors.forename: P C
authors.initials: PC
authors.lastname: Mol
authors.forename: J A
authors.initials: JA
authors.lastname: Shaw
authors.forename: E
authors.initials: E
authors.lastname: Cabib
authors.forename: A
authors.initials: A
authors.lastname: Durán
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D002687:Chitin Synthase / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D009154:Mutation; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014170:Transformation, Genetic
chemical_list: D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C069390:CHS3 protein, S cerevisiae; D002687:Chitin Synthase