Summary: Tetracyclin repressor, C-terminal all-alpha domain
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Tetracyclin repressor, C-terminal all-alpha domain Provide feedback
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Hinrichs W, Kisker C, Duvel M, Muller A, Tovar K, Hillen W, Saenger W; , Science 1994;264:418-420.: Structure of the Tet repressor-tetracycline complex and regulation of antibiotic resistance. PUBMED:8153629 EPMC:8153629
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This tab holds annotation information from the InterPro database.
InterPro entry IPR004111
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 the tetracycline transcriptional repressor TetR, which binds to the Tet(A) gene to repress its expression in the absence of tetracycline [PUBMED:7707374]. Tet(A) is a membrane-associated efflux protein that exports tetracycline from the cell before it can attach to ribosomes and inhibit polypeptide chain growth. TetR occurs as a homodimer and uses two helix-turn-helix (HTH) motifs to bind tandem DNA operators, thereby blocking the expression of the associated genes, TetA and TetR. The structure of the class D TetR repressor protein [PUBMED:8153629] involves 10 alpha-helices, with connecting turns and loops. The three N-terminal helices constitute the DNA-binding HTH domain, which has an inverse orientation compared with HTH motifs in other DNA-binding proteins. The core of the protein, formed by helices 5-10, is responsible for dimerisation and contains, for each monomer, a binding pocket that accommodates tetracycline in the presence of a divalent cation.
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|Biological process||negative regulation of transcription, DNA-dependent (GO:0045892)|
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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 9 members:DUF1956 TetR_C TetR_C_2 TetR_C_3 TetR_C_4 TetR_C_5 TetR_C_6 TetR_C_7 TetR_C_9
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Curation and family details
|Seed source:||Structural domain|
|Number in seed:||18|
|Number in full:||1930|
|Average length of the domain:||139.70 aa|
|Average identity of full alignment:||19 %|
|Average coverage of the sequence by the domain:||61.05 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||12|
|Download:||download the raw HMM for this family|
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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 domain has been found. There are 87 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 seqence.
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