Genome-wide investigation of aromatic acid transporters in Corynebacterium glutamicum.
Genome-wide data mining indicated that six genes (ncgl1031, ncgl2302, ncgl2325, ncgl2326, ncgl2922 and ncgl2953) encoding putative transport proteins are involved in uptake of various aromatic compounds that are further degraded through the beta-ketoadipate, gentisate and resorcinol pathways in Corynebacterium glutamicum. The gentisate (GenK/NCgl2922) and vanillate (VanK/NCgl2302) transporters have been identified previously. In this study, physiological functions of the remaining four putative transporters as well as the vanillate transporter (VanK/NCgl2302) were examined by genetic disruption/complementation and uptake assays. Results indicated that ncgl1031 encodes PcaK for 4-hydroxybenzoate and protocatechuate transport, and ncgl2302 encodes VanK for vanillate transport. Genetic studies and uptake assays indicated that both ncgl2325/benK and ncgl2326/benE are involved in benzoate transport in C. glutamicum. When growth rates were compared for two benzoate transporter mutants, benK and benE, a high growth rate was observed for the benE mutant. Sequence alignments revealed that PcaK, VanK, BenK and GenK belong to the major facilitator superfamily (MFS). Modelling of secondary structures based on previously characterized MFS members revealed that NCgl1031, NCgl2302, NCgl2325 and NCgl2922 are typical 12 helix transmembrane proteins but NCgl2326 contains only 11 alpha-helices. Thus the functionally identified NCgl2326 belongs to a novel type of benzoate transporters. Attempts to identify the phenotype of a hydK/ncgl2953 mutant failed, so the function of ncgl2953 remains unclear.
Chaudhry
Muhammad Tausif
MT
Graduate University of Chinese Academy of Sciences, Beijing, 100049, China.|State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, China.
Huang
Yan
Y
Graduate University of Chinese Academy of Sciences, Beijing, 100049, China.|State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, China.
Shen
Xi-Hui
XH
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, China.
Poetsch
Ansgar
A
Lehrstuhl für Biochemie der Pflanzen, Ruhr Universität, Bochum, Germany.
Jiang
Cheng-Ying
CY
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, China.
Liu
Shuang-Jiang
SJ
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, China.
D001565:Benzoates / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology; D048230:Corynebacterium glutamicum / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D023061:Gene Order; D005816:Genetic Complementation Test; D016680:Genome, Bacterial / Q000235:genetics*; D006841:Hydrocarbons, Aromatic / Q000378:metabolism*; D062385:Hydroxybenzoates / Q000378:metabolism; D010226:Parabens / Q000378:metabolism; D010802:Phylogeny; D017386:Sequence Homology, Amino Acid; D014641:Vanillic Acid / Q000378:metabolism
D001565:Benzoates; D002352:Carrier Proteins; D006841:Hydrocarbons, Aromatic; D062385:Hydroxybenzoates; D010226:Parabens; C009091:protocatechuic acid; D014641:Vanillic Acid; C038193:4-hydroxybenzoic acid