title: Lactate utilization is regulated by the FadR-type regulator LldR in Pseudomonas aeruginosa.
abstract: NAD-independent L-lactate dehydrogenase (l-iLDH) and NAD-independent D-lactate dehydrogenase (D-iLDH) activities are induced coordinately by either enantiomer of lactate in Pseudomonas strains. Inspection of the genomic sequences of different Pseudomonas strains revealed that the lldPDE operon comprises 3 genes, lldP (encoding a lactate permease), lldD (encoding an L-iLDH), and lldE (encoding a D-iLDH). Cotranscription of lldP, lldD, and lldE in Pseudomonas aeruginosa strain XMG starts with the base, C, that is located 138 bp upstream of the lldP ATG start codon. The lldPDE operon is located adjacent to lldR (encoding an FadR-type regulator, LldR). The gel mobility shift assays revealed that the purified His-tagged LldR binds to the upstream region of lldP. An XMG mutant strain that constitutively expresses D-iLDH and L-iLDH was found to contain a mutation in lldR that leads to an Ile23-to-serine substitution in the LldR protein. The mutated protein, LldR(M), lost its DNA-binding activity. A motif with a hyphenated dyad symmetry (TGGTCTTACCA) was identified as essential for the binding of LldR to the upstream region of lldP by using site-directed mutagenesis. L-Lactate and D-lactate interfered with the DNA-binding activity of LldR. Thus, L-iLDH and D-iLDH were expressed when the operon was induced in the presence of L-lactate or D-lactate.
authors.affiliation: State Key Laboratory of Microbial Technology, Shandong University, Jinan, People's Republic of China.
authors.forename: Chao
authors.initials: C
authors.lastname: Gao
authors.forename: Chunhui
authors.initials: C
authors.lastname: Hu
authors.forename: Zhaojuan
authors.initials: Z
authors.lastname: Zheng
authors.forename: Cuiqing
authors.initials: C
authors.lastname: Ma
authors.forename: Tianyi
authors.initials: T
authors.lastname: Jiang
authors.forename: Peipei
authors.initials: P
authors.lastname: Dou
authors.forename: Wen
authors.initials: W
authors.lastname: Zhang
authors.forename: Bin
authors.initials: B
authors.lastname: Che
authors.forename: Yujiao
authors.initials: Y
authors.lastname: Wang
authors.forename: Min
authors.initials: M
authors.lastname: Lv
authors.forename: Ping
authors.initials: P
authors.lastname: Xu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D016680:Genome, Bacterial; D023281:Genomics / Q000379:methods; D007773:Lactates / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009842:Oligopeptides; D009876:Operon; D011485:Protein Binding; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D007773:Lactates; C096894:MUT 1 peptide; D009842:Oligopeptides; D014157:Transcription Factors