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GalS DNA-binding transcriptional dual regulator

Synonyms: GalS, GalS-galactose
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 [2, 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 [2, 3, 5, 6] GalS is negatively autoregulated, and its expression is increased in the presence of inducer and glucose [2, 3]
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 [2, 5] 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 [BPP], [GEA], [IDA], [IPI] [1], [2], [3]
GalS-galactose Non-Functional Allosteric Holo [BPP], [GEA], [IDA], [IPI] [1], [2], [3]
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,-](6)
[GalS,+-](1)


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 -60.5 -86.5 galE, galT, galK, galM
ctaaattcttGTGTAAACGATTCCACtaatttattc
792134 792149 [BPP], [GEA], [HIBSCS] [2], [3], [4], [5], [6]
  GalS repressor galEp1 Sigma70 52.5 25.5 galE, galT, galK, galM
tctggttaccGGTGGTAGCGGTTACAttggaagtca
792022 792037 [BPP], [GEA], [HIBSCS] [2], [3], [4], [5], [6]
  GalS repressor galEp2 Sigma70 -55.5 -86.5 galE, galT, galK, galM
ctaaattcttGTGTAAACGATTCCACtaatttattc
792134 792149 [BPP], [GEA], [HIBSCS] [2], [3], [4], [5], [6]
  GalS-galactose activator galEp2 Sigma70 -55.5 -86.5 galE, galT, galK, galM
ctaaattcttGTGTAAACGATTCCACtaatttattc
792134 792149 [BPP], [GEA], [HIBSCS] [2], [3], [4], [5], [6]
  GalS repressor galEp2 Sigma70 57.5 25.5 galE, galT, galK, galM
tctggttaccGGTGGTAGCGGTTACAttggaagtca
792022 792037 [BPP], [GEA], [HIBSCS] [2], [3], [4], [5], [6]
  GalS-galactose repressor galPp Sigma70 -243.5 -272.5 galP
atcatcacaaCTGAAACCGATTACACcaaccacaac
3088004 3088019 [AIBSCS], [BPP], [SM] [7]
  GalS-galactose repressor galPp Sigma70 -207.5 -236.5 galP
agacaaagatTTGTAATATTTTCATAttattattcg
3088040 3088055 [AIBSCS], [BPP] [7]
  GalS-galactose repressor galPp Sigma70 -178.5 -207.5 galP
ttattcggttTTCACAGTTGTTACATttcttttcag
3088069 3088084 [AIBSCS], [BPP], [SM] [7]
  GalS-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] [2], [4], [6], [7]
  GalS repressor galPp Sigma70 136.5 106.5 galP
cctggatatcGGTGTAATTGCTGGCGcactgccgtt
3088383 3088398 [BPP], [GEA], [SM] [2], [4], [6], [7]
  GalS-galactose repressor galRp Sigma70 8.5 -22.5 galR
cactgaaagaATGTAAGCGTTTACCCactaaggtat
2976569 2976584 [GEA], [HIBSCS] [4]
  GalS repressor galSp Sigma70 -61.5 -103.5 galS
aacaaaacggCTGTAACCGTTTCCATtgctgtgact
2241764 2241779 [BCE], [GEA] [3], [4]
  GalS repressor galSp Sigma70 92.5 49.5 galS
tggcgtctctGTGGCAACGGTTTCCCgggtgctcaa
2241611 2241626 [BCE], [GEA] [3], [4]
  GalS repressor mglBp Sigma70 -59.5 -277.5 mglB, mglA, mglC
aaatcaggcgATGTAACCGCTTTCAAtctgtgagtg
2240618 2240633 [GEA], [HIBSCS] [2], [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    

 [BPP] Binding of purified proteins

 [GEA] Gene expression analysis

 [IDA] Inferred from direct assay

 [IPI] Inferred from physical 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] Dalma-Weiszhausz DD., Brenowitz M., 1996, Interactions between RNA polymerase and the positive and negative regulators of transcription at the Escherichia coli gal operon., Biochemistry. 35(12):3735-45

 [2] 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

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

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

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

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

 [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

 [9] Golding A., Weickert MJ., Tokeson JP., Garges S., Adhya S., 1991, A mutation defining ultrainduction of the Escherichia coli gal operon., J Bacteriol. 173(19):6294-6



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