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GalS DNA-binding transcriptional dual regulator

Synonyms: GalS-β-D-galactose, GalS
Summary:
The "Galactose isorepressor," GalS, is a DNA-binding transcription factor that represses transcription of the operons involved in transport and catabolism of D-galactose [1, 3, 4, 5, 6]. Synthesis of these operons is induced when E. coli is grown in the presence of the inducer (D-galactose) and the absence glucose [1, 3, 4, 5] GalS is negatively autoregulated, and its expression is increased in the presence of inducer and glucose [1, 5] On the other hand, GalS is highly homologous in its amino acid sequence to GalR (55% identical and 88% similar); apparently both act together and are capable of cross-talking to regulate expression of the gal regulon [1, 3] For this reason these regulators bind the same operators, in the cis regulatory regions, with different affinities. In the presence of an inductor, GalS undergoes a conformational change that reduces its affinity for the operator.
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Transcription factor      
TF conformation(s):
Name Conformation Type TF-Effector Interaction Type Apo/Holo Conformation Evidence (Confirmed, Strong, Weak) References
GalS Functional   Apo [APPH], [BPP], [GEA], [HIFS], [IDA], [IEP], [IMP], [IPI] [1], [2], [3], [4], [5]
GalS-β-D-galactose Non-Functional Allosteric Holo [APPH], [BPP], [GEA], [HIFS], [IDA], [IEP], [IGI], [IPI] [1], [3], [5]
Evolutionary Family: GalR/LacI
Sensing class: Sensing external and internal signals
Connectivity class: Local Regulator
Gene name: galS
  Genome position: 2240628-2241668
  Length: 1041 bp / 346 aa
Operon name: galS
TU(s) encoding the TF:
Transcription unit        Promoter
galS
galSp


Regulon       
Regulated gene(s) galE, galK, galM, galP, galR, galS, galT, mglA, mglB, mglC
Multifun term(s) of regulated gene(s) MultiFun Term (List of genes associated to the multifun term)
carbon compounds (10)
colanic acid (M antigen) (3)
galactose metabolism (3)
capsule (M and K antigens) (3)
membrane (2)
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Regulated operon(s) galETKM, galP, galR, galS, mglBAC
First gene in the operon(s) galE, galE, galE, galE, galE, galE, galE, galE, galP, galR, galS, mglB
Simple and complex regulons CRP,FlhDC,GalR,GalS
CRP,GalR,GalS
CRP,GalR,GalS,H-NS,HU
CRP,GalR,GalS,HU
CRP,GalR,GalS,NagC
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Simple and complex regulatory phrases Regulatory phrase (List of promoters regulated by the phrase)
[GalS,+-](1)
[GalS,-](6)


Transcription factor regulation    


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
  GalS repressor galEp1 Sigma70, Sigma38 -60.5 -86.5 galE, galT, galK, galM
gaataaattaGTGGAATCGTTTACACaagaatttag
792134 792149 [BPP], [GEA], [HIBSCS] [1], [3], [4], [5], [6]
  GalS repressor galEp1 Sigma70, Sigma38 52.5 25.5 galE, galT, galK, galM
tgacttccaaTGTAACCGCTACCACCggtaaccaga
792022 792037 [BPP], [GEA], [HIBSCS] [1], [3], [4], [5], [6]
  GalS dual galEp2 Sigma70 -55.5 -86.5 galE, galT, galK, galM
gaataaattaGTGGAATCGTTTACACaagaatttag
792134 792149 [BPP], [GEA], [HIBSCS] [1], [3], [4], [5], [6]
  GalS-β-D-galactose dual galEp2 Sigma70 -55.5 -86.5 galE, galT, galK, galM
gaataaattaGTGGAATCGTTTACACaagaatttag
792134 792149 [BPP], [GEA], [HIBSCS] [1], [3], [4], [5], [6]
  GalS repressor galEp2 Sigma70 57.5 25.5 galE, galT, galK, galM
tgacttccaaTGTAACCGCTACCACCggtaaccaga
792022 792037 [BPP], [GEA], [HIBSCS] [1], [3], [4], [5], [6]
  GalS-β-D-galactose repressor galPp Sigma70 -243.5 -272.5 galP
atcatcacaaCTGAAACCGATTACACcaaccacaac
3088004 3088019 [AIBSCS], [BPP], [SM] [7]
  GalS-β-D-galactose repressor galPp Sigma70 -207.5 -236.5 galP
agacaaagatTTGTAATATTTTCATAttattattcg
3088040 3088055 [AIBSCS], [BPP] [7]
  GalS-β-D-galactose repressor galPp Sigma70 -178.5 -207.5 galP
ttattcggttTTCACAGTTGTTACATttcttttcag
3088069 3088084 [AIBSCS], [BPP], [SM] [7]
  GalS-β-D-galactose repressor galPp Sigma70 -107.5 -136.5 galP
tgatgatataACTCAATTATTTTCATgcacttaaat
3088140 3088155 [AIBSCS], [BPP], [SM] [7]
  GalS repressor galPp Sigma70 -61.5 -90.5 galP
ataaatgttaGTGTAAGCGATTACACtgatgtgatt
3088186 3088201 [BPP], [GEA], [SM] [1], [4], [6], [7]
  GalS repressor galPp Sigma70 136.5 106.5 galP
cctggatatcGGTGTAATTGCTGGCGcactgccgtt
3088383 3088398 [BPP], [GEA], [SM] [1], [4], [6], [7]
  GalS-β-D-galactose repressor galRp Sigma70 8.5 -22.5 galR
cactgaaagaATGTAAGCGTTTACCCactaaggtat
2976569 2976584 [GEA], [HIBSCS] [6]
  GalS repressor galSp Sigma70 -61.5 -103.5 galS
agtcacagcaATGGAAACGGTTACAGccgttttgtt
2241764 2241779 [BCE], [GEA] [5], [6]
  GalS repressor galSp Sigma70 92.5 49.5 galS
ttgagcacccGGGAAACCGTTGCCACagagacgcca
2241611 2241626 [BCE], [GEA] [5], [6]
  GalS repressor mglBp Sigma70, Sigma38 -59.5 -277.5 mglB, mglA, mglC
cactcacagaTTGAAAGCGGTTACATcgcctgattt
2240618 2240633 [GEA], [HIBSCS] [1], [3], [4], [5], [6], [8]


Alignment and PSSM for GalS TFBSs    

Position weight matrix (PWM).   
A	5	0	0	4	12	12	4	1	3	3	0	2	3	2	10
C	2	0	0	0	0	0	6	8	0	6	0	0	5	9	0
G	5	2	12	0	0	0	0	0	9	0	0	3	2	1	2
T	0	10	0	8	0	0	2	3	0	3	12	7	2	0	0

PWM logo   


 


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


Evidence    

 [APPH] Assay of protein purified to homogeneity

 [BPP] Binding of purified proteins

 [GEA] Gene expression analysis

 [HIFS] Human inference of function from sequence

 [IDA] Inferred from direct assay

 [IEP] Inferred from expression pattern

 [IMP] Inferred from mutant phenotype

 [IPI] Inferred from physical interaction

 [IGI] Inferred from genetic interaction

 [HIBSCS] Human inference based on similarity to consensus sequences

 [AIBSCS] Automated inference based on similarity to consensus sequences

 [SM] Site mutation

 [BCE] Binding of cellular extracts



Reference(s)    

 [1] Geanacopoulos M., Adhya S., 1997, Functional characterization of roles of GalR and GalS as regulators of the gal regulon., J Bacteriol 179(1):228-34

 [2] Vermes I., Bonte HA., v d Sluijs Veer G., Schoemaker J., 1991, Interpretations of five monoclonal immunoassays of lutropin and follitropin: effects of normalization with WHO standard., Clin Chem 37(3):415-21

 [3] Weickert MJ., Adhya S., 1992, Isorepressor of the gal regulon in Escherichia coli., J Mol Biol 226(1):69-83

 [4] Weickert MJ., Adhya S., 1993, The galactose regulon of Escherichia coli., Mol Microbiol 10(2):245-51

 [5] Weickert MJ., Adhya S., 1993, Control of transcription of gal repressor and isorepressor genes in Escherichia coli., J Bacteriol 175(1):251-8

 [6] Semsey S., Krishna S., Sneppen K., Adhya S., 2007, Signal integration in the galactose network of Escherichia coli., Mol Microbiol 65(2):465-76

 [7] El Qaidi S., Allemand F., Oberto J., Plumbridge J., 2008, Repression of galP, the galactose transporter in Escherichia coli, requires the specific regulator of N-acetylglucosamine metabolism., Mol Microbiol

 [8] Otsuka J., Watanabe H., Mori KT., 1996, Evolution of transcriptional regulation system through promiscuous coupling of regulatory proteins with operons; suggestion from protein sequence similarities in Escherichia coli., J Theor Biol 178(2):183-204



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