The ncgl1108 (PhePCg) gene encodes a new l-Phe transporter in Corynebacterium glutamicum

Corynebacterium glutamicum played a central role in the establishment of fermentative production of amino acids, and it is a model for genetic and physiological studies. The general aromatic amino acid transporter, AroPCg, was the sole functionally identified aromatic amino acid transporter from C. glutamicum. In this study, the ncgl1108 (named as phePCg), which is located upstream of the genetic cluster (ncgl1110 ∼ ncgl1113) for resorcinol catabolism, was identified as a new l-Phe specific transporter from C. glutamicum RES167. The disruption of phePCg resulted in RES167∆ncgl1108, and this mutant showed decreased growth on l-Phe (as nitrogen source) but not on l-Tyr or l-Trp. Uptake assays with unlabeled and 14C-labeled l-Phe and l-Tyr indicated that the mutants RES167∆ncgl1108 showed significant reduction in l-Phe uptake than RES167. Expression of phePCg in RES167∆ncgl1108/pGXKZ1 or RES167∆(ncgl1108-aroPCg)/pGXKZ1 restored their ability to uptake for l-Phe and growth on l-Phe. The uptake of l-Phe was not inhibited by nine amino acids but by l-Tyr. The Km and Vmax values of RES167∆(ncgl1108-aroPCg)/pGXKZ1 for l-Phe were determined to be 10.4 ± 1.5 μM and 1.2 ± 0.1 nmol min−1 (mg DW)−1, respectively, which are different from Km and Vmax values of RES167∆(ncgl1108-aroPCg) for l-Phe [4.0 ± 0.4 μM and 0.6 ± 0.1 nmol min−1 (mg DW)−1]. In conclusion, this PhePCg is a new l-Phe transporter in C. glutamicum.