title: Characterization of sophorolipid biosynthetic enzymes from Starmerella bombicola.
abstract: Altering glycolipid structure by genetic engineering of Starmerella bombicola is a recently started research topic and worthy alternative to the unsuccessful selective feeding strategies conventionally applied to reach this goal. One question to be addressed when expressing heterologous proteins in S. bombicola is the activity of the subsequent biosynthetic enzymes toward such modified substrates. In this scope, we studied the substrate specificity of the UDP-glucosyltransferases UgtA1 and UgtB1, responsible for the stepwise synthesis of sophorolipids from a hydroxylated fatty acid, and that of the acetyltransferase, responsible for acetylation of the sophorolipid molecule. All enzymes showed specificity toward a C18:1 chained acceptor and both glucosyltransferases were highly selective toward the UDP-glucose donor. Severe product inhibition of the glucosyltransferases explains the limited accumulation of sophorolipid intermediates by earlier created single deletion mutants of S. bombicola. Finally, a more detailed study of the acetylation of sophorolipid intermediates sheds light on the enzymatic cascade during synthesis.
authors: Laboratory for Industrial Biotechnology and Biocatalysis (InBio), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium Karen.Saerens@UGent.be.
authors: Karen M J
authors: KM
authors: Saerens
authors: Laboratory for Industrial Biotechnology and Biocatalysis (InBio), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
authors: Inge N A
authors: IN
authors: Van Bogaert
authors: Laboratory for Industrial Biotechnology and Biocatalysis (InBio), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium.
authors: Wim
authors: W
authors: Soetaert
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D014453:Glucuronosyltransferase / Q000378:metabolism*; D006017:Glycolipids / Q000096:biosynthesis*; D004718:Saccharomycetales / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D005227:Fatty Acids; D006017:Glycolipids; D000123:Acetyltransferases; D014453:Glucuronosyltransferase
keywords: Starmerella bombicola; acetyltransferase; biosurfactants; glucosyltransferase; glycolipid; sophorolipid biosynthesis