title: Involvement of hexokinase Hxk1 in glucose catabolite repression of LIP2 encoding extracellular lipase in the yeast Yarrowia lipolytica.
abstract: The yeast Yarrowia lipolytica produces an extracellular lipase encoded by the LIP2 gene. However, very little is known about the mechanisms controlling its expression, especially on glucose media. In this work, the involvement of hexokinase Hxk1 in the glucose catabolite repression of LIP2 was investigated in a lipase overproducing mutant less sensitive to glucose repression. This mutant has a reduced capacity to phosphorylate hexose compared with the wild-type strain, but no differences could be observed between the HXK1 sequences in the two isolates. This suggested that the reduced phosphorylating activity of the mutant strain probably resulted from a modification in the level of HXK1 expression. However, overexpression of the HXK1 gene in this mutant led to a decrease of both LIP2 induction and extracellular lipase activity, suggesting that the hexokinase is involved in the glucose catabolite repression of LIP2 in Y lipolytica.
authors.affiliation: Centre Wallon de Biologie Industrielle, Service de Technologie Microbienne, Université de Liège, Bd du Rectorat Bat. B40, 4000, Liège, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Fickers
authors.forename: Jean Marc
authors.initials: JM
authors.lastname: Nicaud
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Destain
authors.forename: Philippe
authors.initials: P
authors.lastname: Thonart
mesh_terms: D001426:Bacterial Proteins; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D005656:Fungal Proteins; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D005947:Glucose / Q000378:metabolism*; D006593:Hexokinase / Q000378:metabolism*; D008049:Lipase / Q000096:biosynthesis* / Q000235:genetics; D009154:Mutation; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D025062:Yarrowia / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004271:DNA, Fungal; D005656:Fungal Proteins; D006593:Hexokinase; C408971:LIP2 protein, Yarrowia lipolytica; D008049:Lipase; D005947:Glucose