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, AroP (Cg) , was the sole functionally identified aromatic amino acid transporter from C. glutamicum. In this study, the ncgl1108 (named as pheP (Cg) ), which is located upstream of the genetic cluster (ncgl1110 similar to ncgl1113) for resorcinol catabolism, was identified as a new l-Phe specific transporter from C. glutamicum RES167. The disruption of pheP (Cg) resulted in RES167a dagger 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 C-14-labeled l-Phe and l-Tyr indicated that the mutants RES167a dagger ncgl1108 showed significant reduction in l-Phe uptake than RES167. Expression of pheP (Cg) in RES167a dagger ncgl1108/pGXKZ1 or RES167a dagger(ncgl1108-aroP (Cg) )/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 K (m) and V (max) values of RES167a dagger(ncgl1108-aroP (Cg) )/pGXKZ1 for l-Phe were determined to be 10.4 +/- 1.5 mu M and 1.2 +/- 0.1 nmol min(-1) (mg DW)(-1), respectively, which are different from K (m) and V (max) values of RES167a dagger(ncgl1108-aroP (Cg) ) for l-Phe [4.0 +/- 0.4 mu M and 0.6 +/- 0.1 nmol min(-1) (mg DW)(-1)]. In conclusion, this PheP (Cg) is a new l-Phe transporter in C. glutamicum.