title: Improved production of heterologous proteins by a glucose repression-defective mutant of Kluyveromyces lactis.
abstract: The secreted production of heterologous proteins in Kluyveromyces lactis was studied. A glucoamylase (GAA) from the yeast Arxula adeninivorans was used as a reporter protein for the study of the secretion efficiencies of several wild-type and mutant strains of K. lactis. The expression of the reporter protein was placed under the control of the strong promoter of the glyceraldehyde-3-phosphate dehydrogenase of Saccharomyces cerevisiae. Among the laboratory strains tested, strain JA6 was the best producer of GAA. Since this strain is known to be highly sensitive to glucose repression and since this is an undesired trait for biomass-oriented applications, we examined heterologous protein production by using glucose repression-defective mutants isolated from this strain. One of them, a mutant carrying a dgr151-1 mutation, showed a significantly improved capability of producing heterologous proteins such as GAA, human serum albumin, and human interleukin-1beta compared to the parent strain. dgr151-1 is an allele of RAG5, the gene encoding the only hexokinase present in K. lactis (a homologue of S. cerevisiae HXK2). The mutation in this strain was mapped to nucleotide position +527, resulting in a change from glycine to aspartic acid within the highly conserved kinase domain. Cells carrying the dgr151-1 allele also showed a reduction in N- and O-glycosylation. Therefore, the dgr151 strain may be a promising host for the production of heterologous proteins, especially when the hyperglycosylation of recombinant proteins must be avoided.
authors.affiliation: Department of Genetics Anthropology Evolution, University of Parma, Parma, Italy. claudia.donnini@unipr.it
authors.forename: Claudia
authors.initials: C
authors.lastname: Donnini
authors.forename: Francesca
authors.initials: F
authors.lastname: Farina
authors.forename: Barbara
authors.initials: B
authors.lastname: Neglia
authors.forename: Maria Concetta
authors.initials: MC
authors.lastname: Compagno
authors.forename: Daniela
authors.initials: D
authors.lastname: Uccelletti
authors.forename: Paola
authors.initials: P
authors.lastname: Goffrini
authors.forename: Claudio
authors.initials: C
authors.lastname: Palleschi
mesh_terms: D000595:Amino Acid Sequence; D005800:Genes, Fungal; D005087:Glucan 1,4-alpha-Glucosidase / Q000235:genetics / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D006593:Hexokinase / Q000235:genetics* / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D007716:Kluyveromyces / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; D011994:Recombinant Proteins; C064658:RAG-1 protein; D006593:Hexokinase; D005087:Glucan 1,4-alpha-Glucosidase; D005947:Glucose