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10  structures 1885  species 0  interactions 7935  sequences 10  architectures

Family: TetR_C_11 (PF16859)

Summary: Tetracyclin repressor-like, C-terminal domain

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Tetracyclin repressor-like, C-terminal domain Provide feedback

This family of bacterial transcriptional repressors is characterised by the short approximately 50 amino acid stretch of residues constituting the helix-turn-helix DNA binding motif, around the YRFhY motif. The target proteins that are repressed are involved in the transcriptional control of multi-drug efflux pumps, pathways for the biosynthesis of antibiotics, response to osmotic stress and toxic chemicals, control of catabolic pathways, differentiation processes, and pathogenicity [1].

Literature references

  1. Ramos JL, Martinez-Bueno M, Molina-Henares AJ, Teran W, Watanabe K, Zhang X, Gallegos MT, Brennan R, Tobes R;, Microbiol Mol Biol Rev. 2005;69:326-356. : The TetR family of transcriptional repressors. PUBMED:15944459 EPMC:15944459

Internal database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR011075

The antibiotic tetracycline has a broad spectrum of activity, acting to inhibit bacterial protein synthesis by binding to the 30S ribosomal subunit, which prevents the association of the aminoacyl-tRNA to the ribosomal acceptor A site. Tetracycline binding is reversible, therefore diluting out the antibiotic can reverse its effects. Tetracycline resistance genes are often located on mobile elements, such as plasmids, transposons and/or conjugative transposons, which can sometimes be transferred between bacterial species. In certain cases, tetracycline can enhance the transfer of these elements, thereby promoting resistance amongst a bacterial colony. There are three types of tetracycline resistance: tetracycline efflux, ribosomal protection, and tetracycline modification [ PUBMED:16887689 , PUBMED:15837373 ]:

  • Tetracycline efflux proteins belong to the major facilitator superfamily. Efflux proteins are membrane-associated proteins that recognise and export tetracycline from the cell. They are found in both Gram-positive and Gram-negative bacteria [ PUBMED:1423217 ]. There are at least 22 different tetracycline efflux proteins, grouped according to sequence similarity: Group 1 are Tet(A), Tet(B), Tet(C), Tet(D), Tet(E), Tet(G), Tet(H), Tet(J), Tet(Z) and Tet(30); Group 2 are Tet(K) and Tet(L); Group 3 are Otr(B) and Tcr(3); Group 4 is TetA(P); Group 5 is Tet(V). In addition, there are the efflux proteins Tet(31), Tet(33), Tet(V), Tet(Y), Tet(34), and Tet(35).

  • Ribosomal protection proteins are cytoplasmic proteins that display homology with the elongation factors EF-Tu and EF-G. Protection proteins bind the ribosome, causing an alteration in ribosomal conformation that prevents tetracycline from binding. There are at least ten ribosomal protection proteins: Tet(M), Tet(O), Tet(S), Tet(W), Tet(32), Tet(36), Tet(Q), Tet(T), Otr(A), and TetB(P). Both Tet(M) and Tet(O) have ribosome-dependent GTPase activity, the hydrolysis of GTP providing the energy for the ribosomal conformational changes.

  • Tetracycline modification proteins include the enzymes Tet(37) and Tet(X), both of which inactivate tetracycline. In addition, there are the tetracycline resistance proteins Tet(U) and Otr(C).

The expression of several of these tet genes is controlled by a family of tetracycline transcriptional regulators known as TetR. TetR family regulators are involved in the transcriptional control of multidrug efflux pumps, pathways for the biosynthesis of antibiotics, response to osmotic stress and toxic chemicals, control of catabolic pathways, differentiation processes, and pathogenicity [ PUBMED:15944459 ]. The TetR proteins identified in over 115 genera of bacteria and archaea share a common helix-turn-helix (HTH) structure in their DNA-binding domain. However, TetR proteins can work in different ways: they can bind a target operator directly to exert their effect (e.g. TetR binds Tet(A) gene to repress it in the absence of tetracycline), or they can be involved in complex regulatory cascades in which the TetR protein can either be modulated by another regulator or TetR can trigger the cellular response.

This entry represents the C-terminal domain found in a number of different TetR transcription regulator proteins. TetR regulates the expression of the membrane-associated tetracycline resistance protein, TetA, which exports the tetracycline antibiotic out of the cell before it can attach to the ribosomes and inhibit protein synthesis [ PUBMED:7707374 ]. TetR blocks transcription from the genes encoding both TetA and TetR in the absence of antibiotic. The C-terminal domain is multi-helical and is interlocked in the homodimer with the helix-turn-helix (HTH) DNA-binding domain. Other members of the TetR family of transcriptional regulators carry this C-terminal domain. These include:

  • QacR from Staphylococcus aureus, a multidrug binding protein that represses transcription of the qacA multidrug transporter gene [ PUBMED:11739955 ]
  • Ethr, a repressor from Mycobacterium tuberculosis implicated in ethionamide drug resistance [ PUBMED:15236969 ]
  • CprB, a gamma-butyrolactone autoregulator/receptor from Streptomyces coelicolor that acts as a DNA-binding protein [ PUBMED:14757054 ]
  • YcdC, a hypothetical transcriptional regulator from Escherichia coli
  • YsiA, YfiR, and YxaF, hypothetical transcriptional regulators from Bacillus subtilis
  • YbiH, a hypothetical transcriptional regulator from Salmonella typhimurium

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Pfam Clan

This family is a member of clan TetR_C (CL0174), which has the following description:

This clan features families of transcriptional regulators for multidrug efflux pumps, which belong to the TetR superfamily. They are induced by the presence of a variety of factors, such as antibiotics or organic solvents. The C-terminal region featured in these families is thought to contain the inducer-binding site; the divergent sequences in this region allow for the binding of a variety of different inducers [1-4].

The clan contains the following 42 members:

CecR_C COQ9 LuxT_C TetR TetR_C_1 TetR_C_10 TetR_C_11 TetR_C_12 TetR_C_13 TetR_C_14 TetR_C_15 TetR_C_16 TetR_C_17 TetR_C_18 TetR_C_19 TetR_C_2 TetR_C_20 TetR_C_21 TetR_C_22 TetR_C_23 TetR_C_24 TetR_C_25 TetR_C_26 TetR_C_27 TetR_C_28 TetR_C_29 TetR_C_3 TetR_C_30 TetR_C_31 TetR_C_32 TetR_C_33 TetR_C_34 TetR_C_35 TetR_C_36 TetR_C_37 TetR_C_38 TetR_C_4 TetR_C_5 TetR_C_6 TetR_C_7 TetR_C_8 TetR_C_9


We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets and the UniProtKB sequence database. More...

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This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

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Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation View help on the curation process

Seed source: pdb_2id3
Previous IDs: none
Type: Domain
Sequence Ontology: SO:0000417
Author: Coggill P
Number in seed: 294
Number in full: 7935
Average length of the domain: 111 aa
Average identity of full alignment: 21 %
Average coverage of the sequence by the domain: 54.67 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 32.0 32.0
Trusted cut-off 32.0 32.0
Noise cut-off 31.9 31.9
Model length: 113
Family (HMM) version: 8
Download: download the raw HMM for this family

Species distribution

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Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the TetR_C_11 domain has been found. There are 10 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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