SMART: HTH_LACI domain annotation

HTH_LACI helix_turn _helix lactose operon repressor

SMART accession number:	SM00354
Description:
Interpro abstract (IPR000843):	Numerous bacterial transcription regulatory proteins bind DNA via a helix-turn-helix (HTH) motif. These proteins are very diverse, but for convenience may be grouped into subfamilies on the basis of sequence similarity. One such family groups together a range of proteins, including ascG, ccpA, cytR, ebgR, fruR, galR, galS, lacI, malI, opnR, purF, rafR, rbtR and scrR [(PUBMED:1639817), (PUBMED:1805309)]. Within this family, the HTH motif is situated towards the N terminus.
GO process:	regulation of transcription, DNA-dependent (GO:0006355)
GO component:	intracellular (GO:0005622)
GO function:	sequence-specific DNA binding transcription factor activity (GO:0003700)
Family alignment:	View or

There are 8985 HTH_LACI domains in 8977 proteins in SMART's nrdb database.

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Evolution (species in which this domain is found)
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Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
- Nguyen CC, SaierMHJ r
- Phylogenetic, structural and functional analyses of the LacI-GalR family of bacterial transcription factors.
- FEBS Lett. 1995; 377: 98-102
- Display abstract
- Phylogenetic tree construction for 25 sequenced members of the LacI-GalR family (LGF) of transcription factors revealed that almost all branches are similar in length, radiating essentially from a single point. This observation suggests that most of these proteins arose by duplication events which occurred at a specific time in evolutionary history, and that further duplication events were rare. Analyses of the multiple alignment of the LGF proteins lead to suggestions regarding structure-function relationships and reveal that the helix-turn-helix DNA-binding motif of LGF proteins is similar in sequence to those of numerous non-homologous DNA-binding proteins.
- Weickert MJ, Adhya S
- A family of bacterial regulators homologous to Gal and Lac repressors.
- J Biol Chem. 1992; 267: 15869-74
- Display abstract
- We describe a family of proteins which regulate transcription of inducible genes in bacteria (GalR-LacI family). An alignment of the proteins in the GalR-LacI family is presented in which these proteins show a very high degree of similarity (60%) throughout the entire sequences. The homology is greatest among the amino-terminal DNA binding domains. Since a portion of the operator sequences occupied by these proteins is also conserved, a similar DNA structure may be required for specific recognition of DNA by members of the GalR-LacI family. Highly conserved motifs involved in effector binding and oligomerization are also identified. This compilation suggests a widespread conservation of these regulators among bacteria, and have strong implications for further study of peptide motifs in domain function, as well as pathways of protein evolution.
- Haydon DJ, Guest JR
- A new family of bacterial regulatory proteins.
- FEMS Microbiol Lett. 1991; 63: 291-5
- Display abstract
- A new family of bacterial regulatory proteins has been identified by sequence similarity. The family contains the repressor of the Bacillus subtilis gluconate operon (GntR), the regulators for histidine utilization in Pseudomonas putida (HutCPp) and Klebsiella aerogenes (HutCKa), the repressor (FadR) of fatty acid degradation in Escherichia coli, a regulator involved in the conjugal transfer of the broad host range plasmid pIJ101 (KorA), and three proteins of unidentified function in E. coli (GenA, P30 and PhnF). The proteins share amino acid sequence similarities in a 69-residue N-terminal region. A helix-turn-helix motif is predicted in the most highly-conserved segment of each protein suggesting that they are members of a new family of helix-turn-helix DNA-binding proteins.
Metabolism (metabolic pathways involving proteins which contain this domain)

Structure (3D structures containing this domain)

3D Structures of HTH_LACI domains in PDB

PDB code	Main view	Title
1bdh		Purine repressor mutant-hypoxanthine-palindromic operator complex
1bdi		Purine repressor mutant-hypoxanthine-palindromic operator complex
1cjg		Nmr structure of lac repressor hp62-dna complex
1efa		Crystal structure of the lac repressor dimer bound to operator and the anti-inducer onpf
1jfs		Purine repressor mutant-hypoxanthine-purf operator complex
1jft		Purine repressor mutant-hypoxanthine-purf operator complex
1jh9		Purine repressor mutant-hypoxanthine-purf operator complex
1jwl		Structure of the dimeric lac repressor/operator o1/onpf complex
1jye		Structure of a dimeric lac repressor with c-terminal deletion and k84l substitution
1jyf		Structure of the dimeric lac repressor with an 11-residue c- terminal deletion.
1l1m		Solution structure of a dimer of lac repressor dna-binding domain complexed to its natural operator o1
1lbg		Lactose operon repressor bound to 21-base pair symmetric operator dna, alpha carbons only
1lbh		Intact lactose operon repressor with gratuitous inducer iptg
1lbi		Lac repressor
1lcc		Structure of the complex of lac repressor headpiece and an base-pair half-operator determined by nuclear magnetic resonance spectroscopy and restrained molecular dynamics
1lcd		Structure of the complex of lac repressor headpiece and an base-pair half-operator determined by nuclear magnetic resonance spectroscopy and restrained molecular dynamics
1lqc		Lac repressor headpiece (residues 1-56), nmr, 32 structures
1osl		Solution structure of a dimeric lactose dna-binding domain complexed to a nonspecific dna sequence
1pnr		Purine repressor-hypoxanthine-purf-operator complex
1pru		Purine repressor dna-binding domain dna binding
1prv		Purine repressor dna-binding domain dna binding
1qp0		Purine repressor-hypoxanthine-palindromic operator complex
1qp4		Purine repressor-hypoxanthine-palindromic operator complex
1qp7		Purine repressor mutant-hypoxanthine-palindromic operator complex
1qpz		Purine repressor-hypoxanthine-palindromic operator complex
1qqa		Purine repressor mutant-hypoxanthine-palindromic operator complex
1qqb		Purine repressor mutant-hypoxanthine-palindromic operator complex
1rzr		Crystal structure of transcriptional regulator- phosphoprotein-dna complex
1uxc		Fructose repressor dna-binding domain, nmr, minimized structure
1uxd		Fructose repressor dna-binding domain, nmr, 34 structures
1vpw		Structure of the purr mutant, l54m, bound to hypoxanthine and purf operator dna
1wet		Structure of the purr-guanine-purf operator complex
1zay		Purine repressor-hypoxanthine-modified-purf-operator complex
1zvv		Crystal structure of a ccpa-crh-dna complex
2bjc		Nmr structure of a protein-dna complex of an altered specificity mutant of the lac repressor headpiece that mimics the gal repressor
2hsg		Structure of transcription regulator ccpa in its dna-free state
2iks		Crystal structure of n-terminal truncated dna-binding transcriptional dual regulator from escherichia coli k12
2jcg		Apo form of the catabolite control protein a (ccpa) from bacillus megaterium, with the dna binding domain
2kei		Refined solution structure of a dimer of lac repressor dna- binding domain complexed to its natural operator o1
2kej		Solution structure of a dimer of lac repressor dna-binding domain complexed to its natural operator o2
2kek		Solution structure of a dimer of lac repressor dna-binding domain complexed to its natural operator o3
2o20		Crystal structure of transcription regulator ccpa of lactococcus lactis
2pe5		Crystal structure of the lac repressor bound to onpg in repressed state
2pua		Crystal structure of the laci family member, purr, bound to dna: minor groove binding by alpha helices
2pub		Crystal structure of the laci family member, purr, bound to dna: minor groove binding by alpha helices
2puc		Crystal structure of the laci family member, purr, bound to dna: minor groove binding by alpha helices
2pud		Crystal structure of the laci family member, purr, bound to dna: minor groove binding by alpha helices
2pue		Crystal structure of the laci family member, purr, bound to dna: minor groove binding by alpha helices
2puf		Crystal structure of the laci family member, purr, bound to dna: minor groove binding by alpha helices
2pug		Crystal structure of the laci family member, purr, bound to dna: minor groove binding by alpha helices
3bil		Crystal structure of a probable laci family transcriptional regulator from corynebacterium glutamicum
3ctp		Crystal structure of periplasmic binding protein/laci transcriptional regulator from alkaliphilus metalliredigens qymf complexed with d-xylulofuranose
3dbi		Crystal structure of sugar-binding transcriptional regulator (laci family) from escherichia coli complexed with phosphate
3e3m		Crystal structure of a laci family transcriptional regulator from silicibacter pomeroyi
3edc		Crystal structure of a 1.6-hexanediol bound tetrameric form of escherichia coli lac-repressor refined to 2.1 resolution
3h5o		The crystal structure of transcription regulator gntr from chromobacterium violaceum
3h5t		Crystal structure of a transcriptional regulator, lacl family protein from corynebacterium glutamicum
3jvd		Crystal structure of putative transcription regulation repressor (laci family) from corynebacterium glutamicum
3kjx		Crystal structure of a transcriptional regulator, lacl family protein from silicibacter pomeroyi

Links (links to other resources describing this domain)
PFAM lacI
INTERPRO IPR000843
PROSITE HTH_LACI_FAMILY

PFAM	lacI
INTERPRO	IPR000843
PROSITE	HTH_LACI_FAMILY