Moreover, they were also the most favourable substrates. It is possible that acetate and propionate were transported by the same transport system but further confirmation is required

as Candidatus Competibacter phosphatis appeared to have different transporters for the two solutes [21]. Another acetate permease, ActP of Rhodobacter capsulatus, was produced around 1.5 folds more in acetate- than in pyruvate-grown cells [22]. This indicated that the regulations of various acetate-transport systems in different bacteria are likely to be different and should be compared cautiously. It is not surprising that MCA-grown cells could take up MCA and acetate because most transporters recognize more than one substrate. Acetate permease ActP of E. coli was able to transport acetate and glycolate [17]. Moreover, acetate and MCA are structurally similar selleck chemicals llc molecules. The ability for MCA-grown cells to transport acetate can be explained by (1) the capability of the induced MCA-transport system to transport acetate; (2) the acetate-transport system was also

induced by MCA; and (3) both (1) and (2). Without the identification of the individual permease involved in each of the transport system it is difficult to determine conclusively which the case is. The cloning and heterologous expression of Deh4p in E. coli demonstrated its function as a dehalogenase-associated MCA-transporter [13]. Similarly, the functional role of Dehp2 as a second MCA-transporter was also demonstrated [15]. Both Deh4p and Dehp2 were capable of recognizing acetate as a substrate. In order to elucidate that the MCA-uptake system, comprising Deh4p and Dehp2, is not the JIB04 main transporter for acetate, a deh4p ‒ dehp2 ‒ double mutant (strain Ins-4p-p2, [15]) was utilized. Figure 6A shows that the growth of Ins-4p-p2 on acetate was similar to that of wildtype MBA4, if not slightly better. The acetate-uptake rate of this acetate-grown mutant was also assayed and shown to

be similar to that of wildtype (112.3 nmol (mg protein)-1 min-1 for mutant and 118.6 nmol (mg protein)-1 min-1 for wildtype, Figure 6B). This suggested that PIK3C2G in the absence of the major players in MCA uptake the growth and uptake activity on acetate of the cell were not affected. This confirmed the presence of an independent acetate-transport system other than the MCA-uptake system. Figure 6 Growth on and uptake of acetate of a deh4p – dehp2 – double mutant. (A) Wildtype MBA4 (■) and deh4p – dehp2 – double mutant (□) were grown in minimal medium containing acetate. Seed cultures were grown in LB– and sub-cultured into minimal medium containing acetate at 30°C. The optical densities of the cultures were determined at 600 nm (OD600) with a spectrophotometer. (B) Acetate-uptake rates of acetate-grown- wildtype and double mutant. Uptakes of 50 μM of [2-14C]acetate were assayed by a filtration method for a period of 2 min.