Helix-turn-helix#Classification of helix-turn-helix motifs
{{Short description|Structural motif capable of binding DNA}}
Image:Lambda repressor 1LMB.png employs two helix-turn-helix motifs (left; green) to bind DNA (right; blue and red). The λ repressor protein in this image is a dimer.]]
{{Infobox protein family
| Symbol = HTH
| Name = Helix-turn-helix
| image =
| width =
| caption =
| Pfam =
| Pfam_clan = CL0123
| ECOD = 101.1
| InterPro =
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
Helix-turn-helix is a DNA-binding domain (DBD). The helix-turn-helix (HTH) is a major structural motif capable of binding DNA. Each monomer incorporates two α helices, joined by a short strand of amino acids, that bind to the major groove of DNA. The HTH motif occurs in many proteins that regulate gene expression. It should not be confused with the helix–loop–helix motif.{{cite journal | vauthors = Brennan RG, Matthews BW | title = The helix-turn-helix DNA binding motif | journal = The Journal of Biological Chemistry | volume = 264 | issue = 4 | pages = 1903–6 | date = February 1989 | doi = 10.1016/S0021-9258(18)94115-3 | pmid = 2644244 | doi-access = free }}
Discovery
The discovery of the helix-turn-helix motif was based on similarities between several genes encoding transcription regulatory proteins from bacteriophage lambda and Escherichia coli: Cro, CAP, and λ repressor, which were found to share a common 20–25 amino acid sequence that facilitates DNA recognition.{{cite journal | vauthors = Matthews BW, Ohlendorf DH, Anderson WF, Takeda Y | title = Structure of the DNA-binding region of lac repressor inferred from its homology with cro repressor | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 79 | issue = 5 | pages = 1428–32 | date = March 1982 | pmid = 6951187 | pmc = 345986 | doi = 10.1073/pnas.79.5.1428 | bibcode = 1982PNAS...79.1428M | doi-access = free }}{{cite journal | vauthors = Anderson WF, Ohlendorf DH, Takeda Y, Matthews BW | title = Structure of the cro repressor from bacteriophage lambda and its interaction with DNA | journal = Nature | volume = 290 | issue = 5809 | pages = 754–8 | date = April 1981 | pmid = 6452580 | doi = 10.1038/290754a0 | bibcode = 1981Natur.290..754A | s2cid = 4360799 }}{{cite journal | vauthors = McKay DB, Steitz TA | title = Structure of catabolite gene activator protein at 2.9 A resolution suggests binding to left-handed B-DNA | journal = Nature | volume = 290 | issue = 5809 | pages = 744–9 | date = April 1981 | pmid = 6261152 | doi = 10.1038/290744a0 | bibcode = 1981Natur.290..744M | s2cid = 568056 }}{{cite journal | vauthors = Pabo CO, Lewis M | title = The operator-binding domain of lambda repressor: structure and DNA recognition | journal = Nature | volume = 298 | issue = 5873 | pages = 443–7 | date = July 1982 | pmid = 7088190 | doi = 10.1038/298443a0 | bibcode = 1982Natur.298..443P | s2cid = 39169630 }}
Function
The helix-turn-helix motif is a DNA-binding motif. The recognition and binding to DNA by helix-turn-helix proteins is done by the two α helices, one occupying the N-terminal end of the motif, the other at the C-terminus. In most cases, such as in the Cro repressor, the second helix contributes most to DNA recognition, and hence it is often called the "recognition helix". It binds to the major groove of DNA through a series of hydrogen bonds and various Van der Waals interactions with exposed bases. The other α helix stabilizes the interaction between protein and DNA, but does not play a particularly strong role in its recognition. The recognition helix and its preceding helix always have the same relative orientation.{{cite journal | vauthors = Wintjens R, Rooman M | title = Structural classification of HTH DNA-binding domains and protein-DNA interaction modes | journal = Journal of Molecular Biology | volume = 262 | issue = 2 | pages = 294–313 | date = September 1996 | pmid = 8831795 | doi = 10.1006/jmbi.1996.0514 }}
Classification of helix-turn-helix motifs
Several attempts have been made to classify the helix-turn-helix motifs based on their structure and the spatial arrangement of their helices.{{cite journal | vauthors = Suzuki M, Brenner SE | title = Classification of multi-helical DNA-binding domains and application to predict the DBD structures of sigma factor, LysR, OmpR/PhoB, CENP-B, Rapl, and Xy1S/Ada/AraC | journal = FEBS Letters | volume = 372 | issue = 2–3 | pages = 215–21 | date = September 1995 | pmid = 7556672 | doi = 10.1016/0014-5793(95)00988-L | s2cid = 3037519 | doi-access = | bibcode = 1995FEBSL.372..215S }}{{cite journal | vauthors = Aravind L, Anantharaman V, Balaji S, Babu MM, Iyer LM | title = The many faces of the helix-turn-helix domain: transcription regulation and beyond | journal = FEMS Microbiology Reviews | volume = 29 | issue = 2 | pages = 231–62 | date = April 2005 | pmid = 15808743 | doi = 10.1016/j.femsre.2004.12.008 | doi-broken-date = 23 December 2024 | url = https://zenodo.org/record/1258943 }} Some of the main types are described below.
=Di-helical=
The di-helical helix-turn-helix motif is the simplest helix-turn-helix motif. A fragment of Engrailed homeodomain encompassing only the two helices and the turn was found to be an ultrafast independently folding protein domain.{{cite journal | vauthors = Religa TL, Johnson CM, Vu DM, Brewer SH, Dyer RB, Fersht AR | title = The helix-turn-helix motif as an ultrafast independently folding domain: the pathway of folding of Engrailed homeodomain | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 104 | issue = 22 | pages = 9272–7 | date = May 2007 | pmid = 17517666 | pmc = 1890484 | doi = 10.1073/pnas.0703434104 | bibcode = 2007PNAS..104.9272R | doi-access = free }}
=Tri-helical=
An example of this motif is found in the transcriptional activator Myb.{{cite journal | vauthors = Ogata K, Hojo H, Aimoto S, Nakai T, Nakamura H, Sarai A, Ishii S, Nishimura Y | title = Solution structure of a DNA-binding unit of Myb: a helix-turn-helix-related motif with conserved tryptophans forming a hydrophobic core | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 89 | issue = 14 | pages = 6428–32 | date = July 1992 | pmid = 1631139 | pmc = 49514 | doi = 10.1073/pnas.89.14.6428 | bibcode = 1992PNAS...89.6428O | doi-access = free }}
=Tetra-helical=
The tetra-helical helix-turn-helix motif has an additional C-terminal helix compared to the tri-helical motifs. These include the LuxR-type DNA-binding HTH domain found in bacterial transcription factors and the helix-turn-helix motif found in the TetR repressors.{{cite journal | vauthors = Hinrichs W, Kisker C, Düvel M, Müller A, Tovar K, Hillen W, Saenger W | title = Structure of the Tet repressor-tetracycline complex and regulation of antibiotic resistance | journal = Science | volume = 264 | issue = 5157 | pages = 418–20 | date = April 1994 | pmid = 8153629 | doi = 10.1126/science.8153629 | bibcode = 1994Sci...264..418H }} Multihelical versions with additional helices also occur.{{cite journal | vauthors = Iwahara J, Clubb RT | title = Solution structure of the DNA binding domain from Dead ringer, a sequence-specific AT-rich interaction domain (ARID) | journal = The EMBO Journal | volume = 18 | issue = 21 | pages = 6084–94 | date = November 1999 | pmid = 10545119 | pmc = 1171673 | doi = 10.1093/emboj/18.21.6084 }}
=Winged helix-turn-helix=
The winged helix-turn-helix (wHTH) motif is formed by a 3-helical bundle and a 3- or 4-strand beta-sheet (wing). The topology of helices and strands in the wHTH motifs may vary. In the transcription factor ETS wHTH folds into a helix-turn-helix motif on a four-stranded anti-parallel beta-sheet scaffold arranged in the order α1-β1-β2-α2-α3-β3-β4 where the third helix is the DNA recognition helix.{{cite journal | vauthors = Donaldson LW, Petersen JM, Graves BJ, McIntosh LP | title = Solution structure of the ETS domain from murine Ets-1: a winged helix-turn-helix DNA binding motif | journal = The EMBO Journal | volume = 15 | issue = 1 | pages = 125–34 | date = January 1996 | pmid = 8598195 | pmc = 449924 | doi = 10.2210/pdb1etc/pdb }}{{cite journal | vauthors = Sharrocks AD, Brown AL, Ling Y, Yates PR | title = The ETS-domain transcription factor family | journal = The International Journal of Biochemistry & Cell Biology | volume = 29 | issue = 12 | pages = 1371–87 | date = December 1997 | pmid = 9570133 | doi = 10.1016/S1357-2725(97)00086-1 }}
=Other modified helix-turn-helix motifs=
Other derivatives of the helix-turn-helix motif include the DNA-binding domain found in MarR, a regulator of multiple antibiotic resistance, which forms a winged helix-turn-helix with an additional C-terminal alpha helix.{{cite journal | vauthors = Alekshun MN, Levy SB, Mealy TR, Seaton BA, Head JF | title = The crystal structure of MarR, a regulator of multiple antibiotic resistance, at 2.3 A resolution | journal = Nature Structural Biology | volume = 8 | issue = 8 | pages = 710–4 | date = August 2001 | pmid = 11473263 | doi = 10.1038/90429 | s2cid = 19608515 }}
See also
References
{{reflist|32em}}
Further reading
{{refbegin|32em}}
- {{cite journal | vauthors = Struhl K | title = Helix-turn-helix, zinc-finger, and leucine-zipper motifs for eukaryotic transcriptional regulatory proteins | journal = Trends in Biochemical Sciences | volume = 14 | issue = 4 | pages = 137–40 | date = April 1989 | pmid = 2499084 | doi = 10.1016/0968-0004(89)90145-X }}
- {{cite journal | vauthors = Gajiwala KS, Burley SK | title = Winged helix proteins | journal = Current Opinion in Structural Biology | volume = 10 | issue = 1 | pages = 110–6 | date = February 2000 | pmid = 10679470 | doi = 10.1016/S0959-440X(99)00057-3}}
- {{cite journal | vauthors = Santos CL, Tavares F, Thioulouse J, Normand P | title = A phylogenomic analysis of bacterial helix-turn-helix transcription factors | journal = FEMS Microbiology Reviews | volume = 33 | issue = 2 | pages = 411–29 | date = March 2009 | pmid = 19076237 | doi = 10.1111/j.1574-6976.2008.00154.x | doi-access = free }}
- {{cite journal | vauthors = Hoskisson PA, Rigali S | title = Chapter 1: Variation in form and function the helix-turn-helix regulators of the GntR superfamily | journal = Advances in Applied Microbiology | volume = 69 | pages = 1–22 | year = 2009 | pmid = 19729089 | doi = 10.1016/S0065-2164(09)69001-8 | hdl = 2268/25857 | hdl-access = free }}
- {{cite journal | vauthors = Brennan RG | title = The winged-helix DNA-binding motif: another helix-turn-helix takeoff | journal = Cell | volume = 74 | issue = 5 | pages = 773–6 | date = September 1993 | pmid = 8374950 | doi = 10.1016/0092-8674(93)90456-Z | s2cid = 31355349 }}
- {{cite journal | vauthors = Huffman JL, Brennan RG | title = Prokaryotic transcription regulators: more than just the helix-turn-helix motif | journal = Current Opinion in Structural Biology | volume = 12 | issue = 1 | pages = 98–106 | date = February 2002 | pmid = 11839496 | doi = 10.1016/s0959-440x(02)00295-6 }}
{{refend}}
External links
- [http://www.ebi.ac.uk/interpro/DisplayIproEntry?ac=IPR000047#cite-1 Helix-turn-helix motif, lambda-like repressor], from EMBL
- [https://web.archive.org/web/20041029023314/http://www.biochem.arizona.edu/classes/bioc568/PDBfiles/1lmb.pdb Full PDB entry for PDB ID 1LMB]
- [http://www.expasy.org/prosite/PDOC50943 Cro/C1-type HTH domain], [https://prosite.expasy.org/cgi-bin/prosite/prosite_search_full.pl?SEARCH=hth more HTHs] in PROSITE
{{navboxes|title=Pfam infoboxes for Helix-turn-helix domains
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{{Infobox protein family
| Symbol = HTH_1
| Name = Bacterial regulatory helix-turn-helix protein, lysR family
| image =
| width =
| caption =
| Pfam = PF00126
| Pfam_clan = CL0123
| InterPro = IPR000847
| SMART =
| PROSITE = PDOC00043
| MEROPS =
| SCOP = 1al3
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_10
| Name = HTH DNA binding domain
| image =
| width =
| caption =
| Pfam = PF04967
| Pfam_clan = CL0123
| InterPro = IPR007050
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_12
| Name = Ribonuclease R winged-helix domain
| image =
| width =
| caption =
| Pfam = PF08461
| Pfam_clan = CL0123
| InterPro = IPR013668
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_13
| Name = HTH DNA binding domain
| image =
| width =
| caption =
| Pfam = PF11972
| Pfam_clan = CL0123
| InterPro = IPR021068
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_3
| Name = Helix-turn-helix
| image =
| width =
| caption =
| Pfam = PF01381
| Pfam_clan = CL0123
| InterPro = IPR001387
| SMART =
| PROSITE = PDOC50943
| MEROPS =
| SCOP = 1r69
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_5
| Name = Bacterial regulatory protein, arsR family
| image =
| width =
| caption =
| Pfam = PF01022
| Pfam_clan = CL0123
| InterPro = IPR001845
| SMART =
| PROSITE = PDOC00661
| MEROPS =
| SCOP = 1smt
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_6
| Name = Helix-turn-helix domain, rpiR family
| image =
| width =
| caption =
| Pfam = PF01418
| Pfam_clan = CL0123
| InterPro = IPR000281
| SMART =
| PROSITE = PDOC51071
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_7
| Name = Helix-turn-helix domain of resolvase
| image =
| width =
| caption =
| Pfam = PF02796
| Pfam_clan = CL0123
| InterPro = IPR006120
| SMART =
| PROSITE = PDOC00334
| MEROPS =
| SCOP = 1hcr
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_8
| Name = Bacterial regulatory protein, Fis family
| image =
| width =
| caption =
| Pfam = PF02954
| Pfam_clan = CL0123
| InterPro = IPR002197
| SMART =
| PROSITE =
| MEROPS =
| SCOP = 1f36
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_9
| Name = RNA polymerase III subunit RPC82 helix-turn-helix domain
| image =
| width =
| caption =
| Pfam = PF08221
| Pfam_clan = CL0123
| InterPro = IPR013197
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_AraC
| Name = Bacterial regulatory helix-turn-helix proteins, AraC family
| image =
| width =
| caption =
| Pfam = PF00165
| Pfam_clan = CL0123
| InterPro = IPR000005
| SMART =
| PROSITE = PDOC00040
| MEROPS =
| SCOP = 1bl0
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_CodY
| Name = CodY helix-turn-helix domain
| image =
| width =
| caption =
| Pfam = PF08222
| Pfam_clan = CL0123
| InterPro = IPR013198
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_DeoR
| Name = DeoR-like helix-turn-helix domain
| image =
| width =
| caption =
| Pfam = PF08220
| Pfam_clan = CL0123
| InterPro = IPR001034
| SMART =
| PROSITE = PDOC00696
| MEROPS =
| SCOP = 1lk5
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_IclR
| Name = IclR helix-turn-helix domain
| image =
| width =
| caption =
| Pfam = PF09339
| Pfam_clan = CL0123
| InterPro = IPR005471
| SMART =
| PROSITE = PDOC00807
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_Mga
| Name = M protein trans-acting positive regulator (MGA) HTH domain
| image =
| width =
| caption =
| Pfam = PF08280
| Pfam_clan = CL0123
| InterPro = IPR013199
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_OrfB_IS605
| Name = Helix-turn-helix domain
| image =
| width =
| caption =
| Pfam = PF12323
| Pfam_clan = CL0123
| InterPro = IPR021027
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_psq
| Name = helix-turn-helix, Psq domain
| image =
| width =
| caption =
| Pfam = PF05225
| Pfam_clan = CL0123
| InterPro = IPR007889
| SMART =
| PROSITE = PDOC50960
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_Tnp_1
| Name = Transposase
| image =
| width =
| caption =
| Pfam = PF01527
| Pfam_clan = CL0123
| InterPro = IPR002514
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_Tnp_IS630
| Name = Transposase
| image =
| width =
| caption =
| Pfam = PF01710
| Pfam_clan = CL0123
| InterPro = IPR002622
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_Tnp_Mu_1
| Name = Mu DNA-binding domain
| image =
| width =
| caption =
| Pfam = PF02316
| Pfam_clan = CL0123
| InterPro = IPR003314
| SMART =
| PROSITE =
| MEROPS =
| SCOP = 1qpm
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_Tnp_Mu_2
| Name = Mu DNA binding, I gamma subdomain
| image =
| width =
| caption =
| Pfam = PF09039
| Pfam_clan = CL0123
| InterPro = IPR015126
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_Tnp_Tc3_2
| Name = Transposase
| image =
| width =
| caption =
| Pfam = PF01498
| Pfam_clan = CL0123
| InterPro = IPR002492
| SMART =
| PROSITE =
| MEROPS =
| SCOP = 1tc3
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_Tnp_Tc5
| Name = Tc5 transposase DNA-binding domain
| image =
| width =
| caption =
| Pfam = PF03221
| Pfam_clan = CL0123
| InterPro = IPR004906
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_WhiA
| Name = Sporulation Regulator WhiA C terminal domain
| image =
| width =
| caption =
| Pfam = PF02650
| Pfam_clan = CL0123
| InterPro = IPR003802
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
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{{Infobox protein family
| Symbol = HTH_15
| Name = Helix-turn-helix domain of alkylmercury lyase
| image =
| width =
| caption =
| Pfam = PF12324
| Pfam_clan = CL0123
| InterPro =
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_16
| Name = Helix-turn-helix domain
| image =
| width =
| caption =
| Pfam = PF12645
| Pfam_clan = CL0123
| InterPro =
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_17
| Name = Helix-turn-helix domain
| image =
| width =
| caption =
| Pfam = PF12728
| Pfam_clan = CL0123
| InterPro =
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_18
| Name = Helix-turn-helix domain
| image =
| width =
| caption =
| Pfam = PF12833
| Pfam_clan = CL0123
| InterPro =
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_19
| Name = Helix-turn-helix domain
| image =
| width =
| caption =
| Pfam = PF12844
| Pfam_clan = CL0123
| InterPro =
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_20
| Name = Helix-turn-helix domain
| image =
| width =
| caption =
| Pfam = PF12840
| Pfam_clan = CL0123
| InterPro =
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_Tnp_IS1
| Name = InsA C-terminal domain
| image =
| width =
| caption =
| Pfam = PF12759
| Pfam_clan = CL0123
| InterPro =
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_Tnp_IS66
| Name = putative Helix-turn-helix domain of transposase IS66
| image =
| width =
| caption =
| Pfam = PF13005
| Pfam_clan = CL0123
| InterPro =
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_11
| Name = HTH domain
| image =
| width =
| caption =
| Pfam = PF08279
| Pfam_clan = CL0123
| InterPro = IPR013196
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_Tnp_Tc3_1
| Name = Tc3 transposase
| image =
| width =
| caption =
| Pfam = PF11427
| Pfam_clan = CL0123
| InterPro =
| SMART =
| PROSITE =
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_IS21
| Name = IS21 transposase-type HTH
| image =
| width =
| caption =
| Pfam =
| Pfam_clan =
| InterPro = IPR017894
| SMART =
| PROSITE = PS50531
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-break|style=width:22em}}
{{Infobox protein family
| Symbol = HTH_IS408
| Name = IS408 transposase-type HTH
| image =
| width =
| caption =
| Pfam =
| Pfam_clan =
| InterPro = IPR017895
| SMART =
| PROSITE = PS50532
| MEROPS =
| SCOP =
| TCDB =
| OPM family =
| OPM protein =
| CAZy =
| CDD =
}}
{{col-float-end}}
}}
{{Protein secondary structure}}
{{Transcription factors|g3}}
{{DEFAULTSORT:Helix-Turn-Helix}}
Category:Protein structural motifs
Category:Transcription factors