title: Structural and functional characterization of the LldR from Corynebacterium glutamicum: a transcriptional repressor involved in L-lactate and sugar utilization.
abstract: LldR (CGL2915) from Corynebacterium glutamicum is a transcription factor belonging to the GntR family, which is typically involved in the regulation of oxidized substrates associated with amino acid metabolism. In the present study, the crystal structure of LldR was determined at 2.05-A resolution. The structure consists of N- and C-domains similar to those of FadR, but with distinct domain orientations. LldR and FadR dimers achieve similar structures by domain swapping, which was first observed in dimeric assembly of transcription factors. A structural feature of Zn(2+) binding in the regulatory domain was also observed, as a difference from the FadR subfamily. DNA microarray and DNase I footprint analyses suggested that LldR acts as a repressor regulating cgl2917-lldD and cgl1934-fruK-ptsF operons, which are indispensable for l-lactate and fructose/sucrose utilization, respectively. Furthermore, the stoichiometries and affinities of LldR and DNAs were determined by isothermal titration calorimetry measurements. The transcriptional start site and repression of LldR on the cgl2917-lldD operon were analysed by primer extension assay. Mutation experiments showed that residues Lys4, Arg32, Arg42 and Gly63 are crucial for DNA binding. The location of the putative ligand binding cavity and the regulatory mechanism of LldR on its affinity for DNA were proposed.
authors.affiliation: Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan.
authors.forename: Yong-Gui
authors.initials: YG
authors.lastname: Gao
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Itou
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhou
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Masaaki
authors.initials: M
authors.lastname: Wachi
authors.forename: Nobuhisa
authors.initials: N
authors.lastname: Watanabe
authors.forename: Isao
authors.initials: I
authors.lastname: Tanaka
authors.forename: Min
authors.initials: M
authors.lastname: Yao
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D050260:Carbohydrate Metabolism; D048230:Corynebacterium glutamicum / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D020869:Gene Expression Profiling; D019344:Lactic Acid / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; D019344:Lactic Acid; D004247:DNA