|Synonyms: LsrR-4,5-dihydroxy-2,3-pentanedione-P, LsrR, LsrR-4,5-dihydroxy-2,3-pentanedione|
Using particular analysis and high-throughput analysis (microarrays), it was established that LsrR regulates expression of many genes involved in several processes, such as autoinducer 2 uptake and processing [1, 3], biofilm architecture [1, 7], host invasion, stress responses, and foreign DNA, among others . It also regulates the expression of small riboregulators .
LrsR pertains to the quorum-sensing system, which involves autoinducer-based bacterial cell-to-cell communication . It was demonstrated in Salmonella enterica serovar Typhimurium that LsrR directly senses and binds the molecule 4,5-dihydroxy-2,3-pentanedione (DPD), phosphorylated  and dephosphorylated .
Distinct forms of DPD constitute the interconverting molecules family generally called autoinducer 2 (AI-2). The binding of DPD to LsrR inactivates LsrR, but phosphorylated DPD appears to specifically inactivate the action of LsrR on the expression of genes for autoinducer 2 uptake and processing (lsrACDBFG-tam operon) and lsrR itself . On the other hand, it was suggested that dihydroxyacaetone phosphate inhibits binding of DPD to LsrR .Read more >
The structure of the LsrR protein has been analyzed in crystallography and mutational analysis studies, where it was observed that it contains two main domains, the DNA-binding domain located in the N terminus and a ligand-binding domain around the C terminus .
This protein binds to DNA as a tetramer to regulate transcription; however, in the presence of phosphorylated autoinducer 2 (AI-2) or ADP-P, the tetramer dissociates into dimers, and the interaction of LsrR with DNA is greatly reduced .
The structure of LsrR as a tetramer was determined via exclusion chromatography and cross-linking assays . The crystal structure of the LsrR protein complexed with the native signal (phosphor-Al-2, D5P) was determined  D5P is converted into its hydrated form to create strong H-bonds with the carboxyl group of D243 
The lsrR gene is transcribed together with lsrK in an operon , and this last gene encodes a protein that phosphorylates to DPD . The lsrRK operon is transcribed divergently from the lsrACDBFG-tam operon, and both operons are activated by CRP and repressed by LsrR . The expression of lsrR was decreased in uvrY and csrA mutant strains 
lsrR shows differential codon adaptation, resulting in differential translation efficiency signatures, in thermophilic microbes. It was therefore predicted to play a role in the heat shock response. An lsrR deletion mutant was shown to be more sensitive than wild-type specifically to heat shock, but not other stresses .
|Evolutionary Family:||Sugar_binding domain|
|Connectivity class:||Local Regulator|
|Length:||954 bp / 317 aa|
|TU(s) encoding the TF:||
|Regulated gene(s)||lsrA, lsrB, lsrC, lsrD, lsrF, lsrG, lsrK, lsrR, tam|
|Multifun term(s) of regulated gene(s)||
MultiFun Term (List of genes associated to the multifun term)
ABC superfamily, membrane component (2)
ABC superfamily ATP binding cytoplasmic component (1)
ABC superfamily, periplasmic binding component (1)
information transfer (1)
cell processes (1)
Transcription related (1)
unassigned reversible reactions (1)
|Regulated operon(s)||lsrACDBFG-tam, lsrRK|
|First gene in the operon(s)||lsrA, lsrR|
|Simple and complex regulons|
|Simple and complex regulatory phrases||
Regulatory phrase (List of promoters regulated by the phrase)
|Functional conformation||Function||Promoter||Sigma factor||Central Rel-Pos||Distance to first Gene||Genes||Sequence||LeftPos||RightPos||Evidence (Confirmed, Strong, Weak)||References|
|LsrR||repressor||lsrAp||Sigma38||nd||nd||lsrA, lsrC, lsrD, lsrB, lsrF, lsrG, tam||nd||nd||[BPP], [GEA], [SM]||, |
|LsrR||repressor||lsrRp||Sigma70||nd||nd||lsrR, lsrK||nd||nd||[BPP], [GEA], [SM]||, , |
|Evolutionary conservation of regulatory elements|
 Li J., Attila C., Wang L., Wood TK., Valdes JJ., Bentley WE., 2007, Quorum sensing in Escherichia coli is signaled by AI-2/LsrR: effects on small RNA and biofilm architecture., J Bacteriol. 189(16):6011-20
 Xavier KB., Miller ST., Lu W., Kim JH., Rabinowitz J., Pelczer I., Semmelhack MF., Bassler BL., 2007, Phosphorylation and processing of the quorum-sensing molecule autoinducer-2 in enteric bacteria., ACS Chem Biol. 2(2):128-36
 Wang L., Hashimoto Y., Tsao CY., Valdes JJ., Bentley WE., 2005, Cyclic AMP (cAMP) and cAMP receptor protein influence both synthesis and uptake of extracellular autoinducer 2 in Escherichia coli., J Bacteriol. 187(6):2066-76
 Wu M., Tao Y., Liu X., Zang J., 2013, Structural basis for phosphorylated autoinducer-2 modulation of the oligomerization state of the global transcription regulator LsrR from Escherichia coli., J Biol Chem. 288(22):15878-87
 Zhang XS., Garcia-Contreras R., Wood TK., 2008, Escherichia coli transcription factor YncC (McbR) regulates colanic acid and biofilm formation by repressing expression of periplasmic protein YbiM (McbA)., ISME J. 2(6):615-31
 Ha JH., Eo Y., Grishaev A., Guo M., Smith JA., Sintim HO., Kim EH., Cheong HK., Bentley WE., Ryu KS., 2013, Crystal structures of the LsrR proteins complexed with phospho-AI-2 and two signal-interrupting analogues reveal distinct mechanisms for ligand recognition., J Am Chem Soc. 135(41):15526-35