VOL 60 (2019) PAGES 953–962
There was an error when converting the units for ScSPT. This error has been corrected in Fig. 2C and Table 1. The text should be corrected as follows. On page 958, “We used the same L-serine substrate panel (1–5) to measure the rate of the SPT-catalyzed reaction for each substrate, but, unfortunately, it was not possible to measure the Km for scSPT using the convenient DTNB assay because of the difficulty in detecting activity at low L-serine concentrations—purified scSPT is ~33-fold less active than its purified bacterial SpSPT counterpart (Fig. 2B, C, Table 1).” should read as “We used the same L-serine substrate panel (1–5) to measure the rate of the SPT-catalyzed reaction for each substrate, but, unfortunately, it was not possible to measure the Km for scSPT using the convenient DTNB assay because of the difficulty in detecting activity at low L-serine concentrations—purified scSPT is ~333-fold less active than its purified bacterial SpSPT counterpart (Fig. 2B, C, Table 1).” Also, in the same paragraph, “Then, when we measured the rates (12.2 ±0.8, 10.4 ± 2.2, 11.3 ± 0.8, and 12.9 ± 1.9 nmol·min−1·mg−1)using each of the “heavy” L-serine substrates 2–5, respectively, we observed no significant differences (P = 0.5524,0.4621, 0.7185, and 0.3863, respectively) when compared with L-serine 1.” Should read as “Then, when we measured the rates (1.2 ±0.1, 1.0 ± 0.2, 1.1 ± 0.1, and 1.3 ± 0.2 nmol·min−1·mg−1)using each of the “heavy” L-serine substrates 2–5, respectively, we observed no significant differences (P = 0.5524,0.4621, 0.7185, and 0.3863, respectively) when compared with L-serine 1.” This correction does not affect the results or conclusions of this work.
| SpSPT | ScSPT | ||
| KM (mM) | Rate (nmol min−1 mg−1) | Rate (nmol min−1 mg−1) | |
| 1 L-serine | 1.56 ±0.10 | 386.3 ±39.7 | 1.2 ±0.1 |
| 2 [3,3-D] L-serine | 2.72 ±0.29 | 396.7 ±13.1 | 1.2 ±0.1 |
| 3 [2,3,3-D] L-serine | 4.09 ±0.32 | 176.9 ±13.0 | 1.0 ±0.2 |
| 4 [2-13C] L-serine | 3.64 ±0.61 | 410.6 ±25.5 | 1.1 ±0.1 |
| 5 [1,2,3-13C, 2-15N] L-serine | 1.79 ±0.20 | 440.5 ±17.9 | 1.3 ±0.2 |