title: Regulation of the malic enzyme gene malE by the transcriptional regulator MalR in Corynebacterium glutamicum.
abstract: Corynebacterium glutamicum is a Gram-positive nonpathogenic bacterium that is used for the biotechnological production of amino acids. Here, we investigated the transcriptional control of the malE gene encoding malic enzyme (MalE) in C. glutamicum ATCC 13032, which is known to involve the nitrogen regulator AmtR. Gel shift experiments using purified regulators RamA and RamB revealed binding of these regulators to the malE promoter. In DNA-affinity purification experiments a hitherto uncharacterized transcriptional regulator belonging to the MarR family was found to bind to malE promoter DNA and was designated as MalR. C. glutamicum cells overexpressing malR showed reduced MalE activities in LB medium or in minimal media with acetate, glucose, pyruvate or citrate. Deletion of malR positively affected MalE activities during growth in LB medium and minimal media with pyruvate, glucose or the TCA cycle dicarboxylates l-malate, succinate and fumarate. Transcriptional fusion analysis revealed elevated malE promoter activity in the malR deletion mutant during growth in pyruvate minimal medium suggesting that MalR acts as a repressor of malE. Purified MalR bound malE promoter DNA in gel shift experiments. Two MalR binding sites were identified in the malE promoter by mutational analysis. Thus, MalR contributes to the complex transcriptional control of malE which also involves RamA, RamB and AmtR.
authors.affiliation: Chair of Genetics of Prokaryotes, University of Bielefeld, Germany.
authors.forename: Jens P
authors.initials: JP
authors.lastname: Krause
authors.forename: Tino
authors.initials: T
authors.lastname: Polen
authors.forename: Jung-Won
authors.initials: JW
authors.lastname: Youn
authors.forename: Denise
authors.initials: D
authors.lastname: Emer
authors.forename: Bernhard J
authors.initials: BJ
authors.lastname: Eikmanns
authors.forename: Volker F
authors.initials: VF
authors.lastname: Wendisch
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D016384:Consensus Sequence; D048230:Corynebacterium glutamicum / Q000201:enzymology / Q000235:genetics*; D008291:Malate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D017384:Sequence Deletion; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C084528:malR protein, bacteria; D008291:Malate Dehydrogenase