RegulonDB RegulonDB 9.2:Regulon Page

LldR DNA-binding transcriptional dual regulator

Synonyms: LldR-L-lactose, LldR, LldR-L-lactate
LldR, formerly named lactate regulator , is a transcription factor that controls expression of genes involved in transport and catabolism of L-lactate [1, 3] This regulator has a dual function and is positively and negatively autoregulated. In the absence of L-lactate and under anaerobic conditions, this regulator repressed the transcription of the lldPRD operon [1] In this repression system, LldR binds to two operators and probably leads to repressor DNA looping [1] Expression of this regulator is also stimulated in presence of L-lactate, and this inductor promotes a conformational change that probably destabilizes the DNA loop, promoting the transcription open complex [1]
On the another hand, the transcription of lldR is also induced upon biofilm formation compared to planktonic growth in both exponential and stationary phases. An lctR mutant is impaired in biofilm formation [4]
LldR is a protein that belongs to the GntR family and, accordingly, this transcriptional repressor family protein is composed of two domains: a conserved N-terminal domain which contains the DNA-binding region, and the carboxy-terminal domain, which is involved in effector binding and oligomerization [3] Read more >

Transcription factor      
TF conformation(s):
Name Conformation Type TF-Effector Interaction Type Apo/Holo Conformation Evidence (Confirmed, Strong, Weak) References
LldR Functional   Apo [BPP], [GEA], [IPI], [SM] [1]
LldR-L-lactate Functional Allosteric Holo [BPP], [GEA], [IPI], [SM] [1]
LldR-L-lactose     nd nd
Evolutionary Family: GntR
Sensing class: Sensing external and internal signals
Connectivity class: Local Regulator
Gene name: lldR
  Genome position: 3779054-3779830
  Length: 777 bp / 258 aa
Operon name: lldPRD
TU(s) encoding the TF:
Transcription unit        Promoter

Regulated gene(s) lldD, lldP, lldR
Multifun term(s) of regulated gene(s) MultiFun Term (List of genes associated to the multifun term)
aerobic respiration (2)
anaerobic respiration (1)
electron donors (1)
carbon compounds (1)
Porters (Uni-, Sym- and Antiporters) (1)
Read more >
Regulated operon(s) lldPRD
First gene in the operon(s) lldP
Simple and complex regulons ArcA,LldR
Simple and complex regulatory phrases Regulatory phrase (List of promoters regulated by the phrase)

Transcription factor binding sites (TFBSs) arrangements       

  Functional conformation Function Promoter Sigma factor Central Rel-Pos Distance to first Gene Genes Sequence LeftPos RightPos Evidence (Confirmed, Strong, Weak) References
  LldR repressor lldPp Sigma70 -97.0 -207.0 lldP, lldR, lldD
3777181 3777203 [AIBSCS], [BPP], [GEA], [SM] [1]
  LldR-L-lactose activator lldPp Sigma70 -97.0 -207.0 lldP, lldR, lldD
3777181 3777203 [AIBSCS], [BPP], [GEA], [SM] [1]
  LldR repressor lldPp Sigma70 30.0 -81.0 lldP, lldR, lldD
3777307 3777329 [AIBSCS], [BPP], [GEA], [HIBSCS], [SM] [1], [2]

Evolutionary conservation of regulatory elements    
     Note: Evolutionary conservation of regulatory interactions and promoters is limited to gammaproteobacteria.
Promoter-target gene evolutionary conservation


 [BPP] Binding of purified proteins

 [GEA] Gene expression analysis

 [IPI] Inferred from physical interaction

 [SM] Site mutation

 [AIBSCS] Automated inference based on similarity to consensus sequences

 [HIBSCS] Human inference based on similarity to consensus sequences


 [1] Aguilera L., Campos E., Gimenez R., Badia J., Aguilar J., Baldoma L., 2008, Dual role of LldR in regulation of the lldPRD operon, involved in L-lactate metabolism in Escherichia coli., J Bacteriol. 190(8):2997-3005

 [2] Lynch AS., Lin EC., 1996, Transcriptional control mediated by the ArcA two-component response regulator protein of Escherichia coli: characterization of DNA binding at target promoters., J Bacteriol. 178(21):6238-49

 [3] Dong JM., Taylor JS., Latour DJ., Iuchi S., Lin EC., 1993, Three overlapping lct genes involved in L-lactate utilization by Escherichia coli., J Bacteriol. 175(20):6671-8

 [4] Beloin C., Valle J., Latour-Lambert P., Faure P., Kzreminski M., Balestrino D., Haagensen JA., Molin S., Prensier G., Arbeille B., Ghigo JM., 2004, Global impact of mature biofilm lifestyle on Escherichia coli K-12 gene expression., Mol Microbiol. 51(3):659-74