TABLE 6.
Regulation of decarboxylase activities in the reference S. cerevisiae strain IME004 (CEN.PK113-5D, p426GPD) and in an isogenic strain expressing a multicopy plasmid-borne ARO10 gene from a constitutive TDH3 promoter, strain IME003a
| Substrate for decarboxylase assay | IME004 [ura3 p426GPD (URA3)]
|
IME003 [ura3 pUDe001 (URA3 TDH3p-ARO10)]
|
||||||
|---|---|---|---|---|---|---|---|---|
| Ethanol
|
Glucose
|
Ethanol
|
Glucose
|
|||||
| (NH4)2SO4 | Phenylalanine | (NH4)2SO4 | Phenylalanine | (NH4)2SO4 | Phenylalanine | (NH4)2SO4 | Phenylalanine | |
| Phenylpyruvate | BDb | 64 ± 1.2 | BD | 67.5 ± 0.7 | 35 ± 5.7 | 76.5 ± 1.5 | BD | 82.75 ± 26.73 |
| α-Ketoisovalerate | BD | 17 ± 2.2 | BD | 19 ± 0 | 19 ± 0 | 21.75 ± 1.7 | BD | 22.4 ± 6.4 |
| α-Ketoisocaproate | BD | 28 ± 3.1 | BD | 29.5 ± 0.7 | 15 ± 1.4 | 30.5 ± 3 | BD | 31.5 ± 9.8 |
| α-Ketomethylvalerate | BD | 23 ± 0.7 | BD | 25.7 ± 3.8 | 12.5 ± 0.7 | 28 ± 4.0 | BD | 28.3 ± 13.6 |
| 3-Methylthio-α-ketobutyrate | BD | 20.5 ± 1.2 | BD | 22 ± 0 | 11 ± 0 | 23.5 ± 1.2 | BD | 24.25 ± 9.1 |
a
Both strains were grown in aerobic, carbon-limited chemostat cultures with glucose or ethanol as a carbon source and ammonia or phenylalanine as a carbon source and ammonia or phenylalanine as a nitrogen source. Enzyme activities were assayed in cell extracts of independent duplicate cultures and are expressed as nmol·min−1·(mg protein)−1. Data are presented as average ± average deviation of the mean of two chemostat cultures.
b
BD, below detection limit.