Fig. 1.
Triterpene accumulation in the yeast S. cerevisiae expressing TkLUP. a Schematic representation of the MVA pathway leading to the synthesis of sterols and pentacyclic triterpenes via oxidosqualene cyclases (OSCs). Dashed arrows represent multiple enzymatic reactions. AACT = acetyl-CoA C-acetyltransferase; DMAPP = dimethylallyl pyrophosphate; IPP = isopentenyl diphosphate; HMGS = 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) synthase; HMGR = HMG-CoA reductase; SQS = squalene synthase; SQE = squalene epoxidase. b Schematic representation of the TkLUP coding sequence under the control of the GAL1 promoter (PGAL1) and CYC1 terminator (TCYC1). c Yeast cells carrying the TkLUP coding sequence showed two additional peaks in the GC-MS spectrum (m/z = 218, arrows), probably representing β-amyrin (retention time = 17.95 min) and lupeol (retention time = 18.25 min) because they match the corresponding standards. d Yeasts carrying the TkLUP coding sequence accumulated 0.16 mg/g CDW of the putative lupeol but the quantification of the β-amyrin peak was not possible. Wild-type (WT) and pAG424_PGAL1-ccdb vector control CEN.PK2-1C cells served as controls. The standard deviation was calculated from n = 3 individual transformants; CDW = cell dry weight