title: Characterization of a Corynebacterium glutamicum lactate utilization operon induced during temperature-triggered glutamate production.
abstract: Gene expression changes of glutamate-producing Corynebacterium glutamicum were identified in transcriptome comparisons by DNA microarray analysis. During glutamate production induced by a temperature shift, C. glutamicum strain 2262 showed significantly higher mRNA levels of the NCgl2816 and NCgl2817 genes than its non-glutamate-producing derivative 2262NP. Reverse transcription-PCR analysis showed that the two genes together constitute an operon. NCgl2816 putatively codes for a lactate permease, while NCgl2817 was demonstrated to encode quinone-dependent l-lactate dehydrogenase, which was named LldD. C. glutamicum LldD displayed Michaelis-Menten kinetics for the substrate l-lactate with a K(m) of about 0.51 mM. The specific activity of LldD was about 10-fold higher during growth on l-lactate or on an l-lactate-glucose mixture than during growth on glucose, d-lactate, or pyruvate, while the specific activity of quinone-dependent d-lactate dehydrogenase differed little with the carbon source. RNA levels of NCgl2816 and lldD were about 18-fold higher during growth on l-lactate than on pyruvate. Disruption of the NCgl2816-lldD operon resulted in loss of the ability to utilize l-lactate as the sole carbon source. Expression of lldD restored l-lactate utilization, indicating that the function of the permease gene NCgl2816 is dispensable, while LldD is essential, for growth of C. glutamicum on l-lactate.
authors.affiliation: Institute of Biotechnology 1, Research Centre Juelich, D-52425 Juelich, Germany.
authors.forename: Corinna
authors.initials: C
authors.lastname: Stansen
authors.forename: Davin
authors.initials: D
authors.lastname: Uy
authors.forename: Stephane
authors.initials: S
authors.lastname: Delaunay
authors.forename: Lothar
authors.initials: L
authors.lastname: Eggeling
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Goergen
authors.forename: Volker F
authors.initials: VF
authors.lastname: Wendisch
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D018698:Glutamic Acid / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism*; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D009876:Operon; D020543:Proteome; D013696:Temperature; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D020543:Proteome; D019344:Lactic Acid; D018698:Glutamic Acid