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3  structures 57  species 0  interactions 59  sequences 6  architectures

Family: FokI_cleav_dom (PF09254)

Summary: FokI, cleavage domain

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This is the Wikipedia entry entitled "FokI". More...

FokI Edit Wikipedia article

Restriction endonuclease Fok1, C terminal
Restriction endonuclease Fok1 bound to DNA PDB 1fok [1]
Pfam clanCL0415

The restriction endonuclease Fok1, naturally found in Flavobacterium okeanokoites, is a bacterial type IIS restriction endonuclease consisting of an N-terminal DNA-binding domain and a non-specific DNA cleavage domain at the C-terminal.[2] Once the protein is bound to duplex DNA via its DNA-binding domain at the 5'-GGATG-3' recognition site, the DNA cleavage domain is activated and cleaves, without further sequence specificity, the first strand 9 nucleotides downstream and the second strand 13 nucleotides upstream of the nearest nucleotide of the recognition site.[3]

Its molecular mass is 65.4 kDa, being composed of 587 amino acids.

DNA-binding domain

The recognition domain contains three subdomains (D1, D2 and D3) that are evolutionarily related to the DNA-binding domain of the catabolite gene activator protein which contains a helix-turn-helix.[3]

DNA-cleavage domain

DNA cleavage is mediated through the non-specific cleavage domain which also includes the dimerisation surface.[4] The dimer interface is formed by the parallel helices α4 and α5 and two loops P1 and P2 of the cleavage domain.[3]


When the nuclease is unbound to DNA, the endonuclease domain is sequestered by the DNA-binding domain and is released through a conformational change in the DNA-binding domain upon binding to its recognition site. Cleavage only occurs upon dimerization, when the recognition domain is bound to its cognate site and in the presence of magnesium ions.[4]


The endonuclease domain of Fok1 has been used in several studies, after combination with a variety of DNA-binding domains such as the zinc finger (see zinc finger nuclease),[2] or inactive Cas9[5][6][7]

One of several human vitamin D receptor gene variants is caused by a single nucleotide polymorphism in the start codon of the gene which can be distinguished through the use of the Fok1 enzyme.[8]


  1. ^ Aggarwal, A. K.; Wah, D. A.; Hirsch, J. A.; Dorner, L. F.; Schildkraut, I. (1997). "Structure of the multimodular endonuclease Fok1 bound to DNA". Nature. 388 (6637): 97–100. doi:10.1038/40446. PMID 9214510. S2CID 205027830.
  2. ^ a b Durai S, Mani M, Kandavelou K, Wu J, Porteus M, Chandrasegaran S (2005). "Zinc finger nucleases: custom-designed molecular scissors for genome engineering of plant and mammalian cells". Nucleic Acids Res. 33 (18): 5978–90. doi:10.1093/nar/gki912. PMC 1270952. PMID 16251401.
  3. ^ a b c Wah, D. A.; Bitinaite, J.; Schildkraut, I.; Aggarwal, A. K. (1998). "Structure of Fok1 has implications for DNA cleavage". Proc Natl Acad Sci USA. 95 (18): 10564–9. Bibcode:1998PNAS...9510564W. doi:10.1073/pnas.95.18.10564. PMC 27934. PMID 9724743.
  4. ^ a b Bitinaite, J.; Wah, D. A.; Aggarwal, A. K.; Schildkraut, I. (1998). "Fok1 dimerization is required for DNA cleavage". Proc Natl Acad Sci USA. 95 (18): 10570–5. Bibcode:1998PNAS...9510570B. doi:10.1073/pnas.95.18.10570. PMC 27935. PMID 9724744.
  5. ^ Tsai, S. Q. et al. (2014). Dimeric CRISPR RNA-guided Fok1 nucleases for highly specific genome editing. Nature Biotechnol. 32, 569–576 doi:10.1038/nbt.2908
  6. ^ Guilinger, J. P., Thompson, D. B. & Liu, D. R. (2014). Fusion of catalytically inactive Cas9 to Fok1 nuclease improves the specificity of genome modification. Nature Biotechnol. 32, 577–582 doi:10.1038/nbt.2909
  7. ^ Wyvekens, N., Topkar, V. V., Khayter, C., Joung, J. K. & Tsai, S. Q. (2015). Dimeric CRISPR RNA-guided Fok1-dCas9 nucleases directed by truncated gRNAs for highly specific genome editing. Hum. Gene Ther. 26, 425–431 doi:10.1089/hum.2015.084
  8. ^ Strandberg, S.; et al. (2003). "Vitamin D receptor start codon polymorphism (Fok1) is related to bone mineral density in healthy adolescent boys". J Bone Miner Metab. 21 (2): 109–13. doi:10.1007/s007740300018. PMID 12601576. S2CID 22436824.

See also

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

FokI, cleavage domain Provide feedback

Members of this family are predominantly found in prokaryotic restriction endonuclease FokI, and adopt a structure consisting of an alpha/beta/alpha core containing a five-stranded beta-sheet. They recognise the double-stranded DNA sequence 5'-GGATG-3' and cleave DNA phosphodiester groups 9 base pairs away on this strand and 13 base pairs away on the complementary strand [1]. This entry represents the C-terminal cleavage domain of FokI.

Literature references

  1. Wah DA, Bitinaite J, Schildkraut I, Aggarwal AK; , Proc Natl Acad Sci U S A. 1998;95:10564-10569.: Structure of FokI has implications for DNA cleavage. PUBMED:9724743 EPMC:9724743

  2. Steczkiewicz K, Muszewska A, Knizewski L, Rychlewski L, Ginalski K;, Nucleic Acids Res. 2012;40:7016-7045.: Sequence, structure and functional diversity of PD-(D/E)XK phosphodiesterase superfamily. PUBMED:22638584 EPMC:22638584

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR015334

This entry represents the C-terminal cleavage domain of FokI, which adopts a structure consisting of an alpha/beta/alpha core containing a five-stranded beta-sheet [ PUBMED:9214510 ].

Type IIS restriction endonuclease FokI ( EC ) is a member of an unusual class of bipartite restriction enzymes that recognises the double-stranded DNA sequence 5'-GGATG-3' and cleave DNA phosphodiester groups 9 base pairs away on this strand and 13 base pairs away on the complementary strand [ PUBMED:9724743 , PUBMED:12093751 ]. FokI contains amino- and carboxy-terminal domains corresponding to the DNA-recognition and cleavage functions, respectively.

The recognition domain is made of three smaller subdomains (D1, D2 and D3) which are evolutionarily related to the helix-turn-helix-containing DNA-binding domain of the catabolite gene activator protein CAP [ PUBMED:9214510 ].

Gene Ontology

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Domain organisation

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Pfam Clan

This family is a member of clan PDDEXK (CL0236), which has the following description:

This clan includes a large number of nuclease families related to holliday junction resolvases [1,2].

The clan contains the following 149 members:

AHJR-like ArenaCapSnatch BamHI BpuJI_N BpuSI_N Bse634I BsuBI_PstI_RE Cas_APE2256 Cas_Cas02710 Cas_Cas4 Cas_Csm6 Cas_DxTHG Cas_NE0113 CdiA_C CdiA_C_tRNase CoiA Csa1 Dna2 DpnI DpnII DpnII-MboI DUF1780 DUF1829 DUF1887 DUF2034 DUF2161 DUF234 DUF2357 DUF2726 DUF2800 DUF2887 DUF3799 DUF4143 DUF4263 DUF4420 DUF559 DUF5614 DUF6035 DUF6293 DUF6671 EC042_2821 EcoRI EcoRII-C eIF-3_zeta Endonuc-BglII Endonuc-BsobI Endonuc-EcoRV Endonuc-HincII Endonuc-MspI Endonuc-PvuII Endonuc_BglI Endonuc_Holl ERCC4 Exo5 Flu_PA FokI_cleav_dom Herpes_UL24 Hjc HSDR_N HSDR_N_2 L_protein_N McrBC MepB-like MmcB-like Mrr_cat Mrr_cat_2 MTES_1575 MutH MvaI_BcnI NaeI NERD NgoMIV_restric NotI NOV_C NucS PDCD9 PDDEXK_1 PDDEXK_10 PDDEXK_11 PDDEXK_12 PDDEXK_2 PDDEXK_3 PDDEXK_4 PDDEXK_5 PDDEXK_7 PDDEXK_9 Pet127 Phage_endo_I PND R-HINP1I Rad10 RAI1 RAP RE_AlwI RE_ApaLI RE_Bpu10I RE_BsaWI RE_Bsp6I RE_CfrBI RE_Eco47II RE_EcoO109I RE_endonuc RE_HaeII RE_HindIII RE_HindVP RE_HpaII RE_LlaJI RE_LlaMI RE_MjaI RE_NgoBV RE_NgoPII RE_SacI RE_ScaI RE_SinI RE_TaqI RE_TdeIII RE_XamI RE_XcyI RecC_C RecU RestrictionMunI RestrictionSfiI RmuC RNA_pol_Rpb5_N Sen15 SfsA Spo0A_C TBPIP_N ThaI Tn7_TnsA-like_N Tox-REase-2 Tox-REase-3 Tox-REase-5 Tox-REase-7 Tox-REase-9 Transposase_31 tRNA_int_endo Tsp45I Uma2 UPF0102 Viral_alk_exo VirArc_Nuclease VRR_NUC Vsr XhoI XisH YaeQ YhcG_C YqaJ


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Curation and family details

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Curation View help on the curation process

Seed source: pdb_2fok
Previous IDs: Endonuc-FokI_C;
Type: Domain
Sequence Ontology: SO:0000417
Author: Sammut SJ
Number in seed: 4
Number in full: 59
Average length of the domain: 169.60 aa
Average identity of full alignment: 30 %
Average coverage of the sequence by the domain: 32.63 %

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 25.0 25.0
Trusted cut-off 25.1 25.3
Noise cut-off 24.7 23.9
Model length: 188
Family (HMM) version: 14
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Archea Archea Eukaryota Eukaryota
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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 FokI_cleav_dom domain has been found. There are 3 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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