Table 6.
Host | Plasmid 1 | Plasmid 2 | SBP present | [14C] Substrate | Uptake kineticsa
|
|
---|---|---|---|---|---|---|
Km | Vmax | |||||
MKH13 | pNcbcXWV | None | CbcX | Choline | 2.6 (0.66) | 34.6 (2.2) |
MKH13 | pNcbcXWV | None | CbcX | Betaine | 24.2 (2.4) | 11.6 (0.6) |
MKH13 | pNcbcWV | pTPA3236 | BetX | Betaine | 0.6 (0.16) | 4.8 (0.18) |
MKH13 | pNchoXWV | None | ChoX | Choline | 1.8 (0.36) | 1.2 (0.05) |
PA5378::tn | pNcbcWV | None | CaiXPAO1 | Carnitine | 24.2 (8.3) | 3.8 (0.33) |
The data were fit with the Michaelis–Menten equation (Fig. S4). The units for the apparent affinity constant (Km) are μM and for the maximal rate of uptake (Vmax) are nmol min−1 (mg protein)−1. Values shown are mean (SE) (n = 4).