Summary: B12 binding domain
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This is the Wikipedia entry entitled "Vitamin B12-binding domain". More...
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Vitamin B12-binding domain Edit Wikipedia article
|SCOP2||1be1 / SCOPe / SUPFAM|
|B12-binding_2 (4-helical bundle cap domain)|
|SCOP2||1bmt / SCOPe / SUPFAM|
In molecular biology, the vitamin B12-binding domain is a protein domain which binds to cobalamin (vitamin B12). It can bind two different forms of the cobalamin cofactor, with cobalt bonded either to a methyl group (methylcobalamin) or to 5'-deoxyadenosine (adenosylcobalamin). Cobalamin-binding domains are mainly found in two families of enzymes present in animals and prokaryotes, which perform distinct kinds of reactions at the cobalt-carbon bond. Enzymes that require methylcobalamin carry out methyl transfer reactions. Enzymes that require adenosylcobalamin catalyse reactions in which the first step is the cleavage of adenosylcobalamin to form cob(II)alamin and the 5'-deoxyadenosyl radical, and thus act as radical generators. In both types of enzymes the B12-binding domain uses a histidine to bind the cobalt atom of cobalamin cofactors. This histidine is embedded in a DXHXXG sequence, the most conserved primary sequence motif of the domain. Proteins containing the cobalamin-binding domain include:
- Animal and prokaryotic methionine synthase (EC 188.8.131.52), which catalyse the transfer of a methyl group from methyl-cobalamin to homocysteine, yielding enzyme-bound cob(I)alamin and methionine.
- Animal and prokaryotic methylmalonyl-CoA mutase (EC 184.108.40.206), which are involved in the degradation of several amino acids, odd-chain fatty acids and cholesterol via propionyl-CoA to the tricarboxylic acid cycle.
- Prokaryotic lysine 5,6-aminomutase (EC 220.127.116.11).
- Prokaryotic glutamate mutase (EC 18.104.22.168).
- Prokaryotic methyleneglutarate mutase (EC 22.214.171.124).
- Prokaryotic isobutyryl-CoA mutase (EC 126.96.36.199).
The core structure of the cobalamin-binding domain is characterised by a five-stranded alpha/beta (Rossmann) fold, which consists of 5 parallel beta-sheets surrounded by 4-5 alpha helices in three layers (alpha/beta/alpha). Upon binding cobalamin, important elements of the binding site appear to become structured, including an alpha-helix that forms on one side of the cleft accommodating the nucleotide 'tail' of the cofactor. In cobalamin, the cobalt atom can be either free (dmb-off) or bound to dimethylbenzimidazole (dmb-on) according to the pH. When bound to the cobalamin-binding domain, the dimethylbenzimidazole ligand is replaced by the active histidine (His-on) of the DXHXXG motif. The replacement of dimethylbenzimidazole by histidine allows switching between the catalytic and activation cycles. In methionine synthase the cobalamin cofactor is sandwiched between the cobalamin-binding domain and an approximately 90 residues N-terminal domain forming a helical bundle comprising two pairs of antiparallel helices. This N-terminal domain forms a 4-helical bundle cap, in the conversion to the active conformation of this enzyme, the 4-helical cap rotates to allow the cobalamin cofactor to bind the activation domain.
- Krautler B (August 2005). "Vitamin B12: chemistry and biochemistry". Biochem. Soc. Trans. 33 (Pt 4): 806â€“10. doi:10.1042/BST0330806. PMIDÂ 16042603.
- Ludwig ML, Matthews RG (1997). "Structure-based perspectives on B12-dependent enzymes". Annu. Rev. Biochem. 66: 269â€“313. doi:10.1146/annurev.biochem.66.1.269. PMIDÂ 9242908.
- Banerjee R, Ragsdale SW (2003). "The many faces of vitamin B12: catalysis by cobalamin-dependent enzymes". Annu. Rev. Biochem. 72: 209â€“47. doi:10.1146/annurev.biochem.72.121801.161828. PMIDÂ 14527323.
- Reitzer R, Gruber K, Jogl G, Wagner UG, Bothe H, Buckel W, Kratky C (August 1999). "Glutamate mutase from Clostridium cochlearium: the structure of a coenzyme B12-dependent enzyme provides new mechanistic insights". Structure. 7 (8): 891â€“902. doi:10.1016/s0969-2126(99)80116-6. PMIDÂ 10467146.
- Hanukoglu I (2015). "Proteopedia: Rossmann fold: A beta-alpha-beta fold at dinucleotide binding sites". Biochem Mol Biol Educ. 43 (3): 206â€“209. doi:10.1002/bmb.20849. PMIDÂ 25704928. S2CIDÂ 11857160.
- Drennan CL, Huang S, Drummond JT, Matthews RG, Lidwig ML (December 1994). "How a protein binds B12: A 3.0 A X-ray structure of B12-binding domains of methionine synthase". Science. 266 (5191): 1669â€“74. doi:10.1126/science.7992050. PMIDÂ 7992050.
- Mancia F, Keep NH, Nakagawa A, Leadlay PF, McSweeney S, Rasmussen B, BÃ¶secke P, Diat O, Evans PR (March 1996). "How coenzyme B12 radicals are generated: the crystal structure of methylmalonyl-coenzyme A mutase at 2 A resolution". Structure. 4 (3): 339â€“50. doi:10.1016/s0969-2126(96)00037-8. PMIDÂ 8805541.
- Bandarian V, Pattridge KA, Lennon BW, Huddler DP, Matthews RG, Ludwig ML (January 2002). "Domain alternation switches B(12)-dependent methionine synthase to the activation conformation". Nat. Struct. Biol. 9 (1): 53â€“6. doi:10.1038/nsb738. PMIDÂ 11731805. S2CIDÂ 10529695.
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.
B12 binding domain Provide feedback
This domain binds to B12 (adenosylcobamide)[1-3], it is found in several enzymes, such as glutamate mutase Q05488 methionine synthase Q99707 and methylmalonyl-CoA mutase P22033. It contains a conserved DxHxxGx(41)SxVx(26)GG motif, which is important for B12 binding .
Tollinger M, Konrat R, Hilbert BH, Marsh EN, Krautler B; , Structure 1998;6:1021-1033.: How a protein prepares for B12 binding: structure and dynamics of the B12-binding subunit of glutamate mutase from Clostridium tetanomorphum. PUBMED:9739092 EPMC:9739092
Perez-Marin MC, Padmanabhan S, Polanco MC, Murillo FJ, Elias-Arnanz M;, Mol Microbiol. 2008;67:804-819.: Vitamin B12 partners the CarH repressor to downregulate a photoinducible promoter in Myxococcus xanthus. PUBMED:18315685 EPMC:18315685
Internal database links
|SCOOP:||adh_short adh_short_C2 FMN_dh IMPDH KR NMO Radical_SAM_N2 Response_reg UPF0004|
|Similarity to PfamA using HHSearch:||Radical_SAM_N Radical_SAM_N2|
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR006158
The cobalamin (vitamin B12) binding domain can bind two different forms of the cobalamin cofactor, with cobalt bonded either to a methyl group (methylcobalamin) or to 5'-deoxyadenosine (adenosylcobalamin). Cobalamin-binding domains are mainly found in two families of enzymes present in animals and prokaryotes, which perform distinct kinds of reactions at the cobalt-carbon bond. Enzymes that require methylcobalamin carry out methyl transfer reactions. Enzymes that require adenosylcobalamin catalyse reactions in which the first step is the cleavage of adenosylcobalamin to form cob(II)alamin and the 5'-deoxyadenosyl radical, and thus act as radical generators. In both types of enzymes the B12-binding domain uses a histidine to bind the cobalt atom of cobalamin cofactors. This histidine is embedded in a DXHXXG sequence, the most conserved primary sequence motif of the domain [ PUBMED:16042603 , PUBMED:9242908 , PUBMED:14527323 ]. Proteins containing the cobalamin-binding domain include:
- Animal and prokaryotic methionine synthase ( EC ), which catalyse the transfer of a methyl group from methyl-cobalamin to homocysteine, yielding enzyme-bound cob(I)alamin and methionine.
- Animal and prokaryotic methylmalonyl-CoA mutase ( EC ), which are involved in the degradation of several amino acids, odd-chain fatty acids and cholesterol via propionyl-CoA to the tricarboxylic acid cycle.
- Prokaryotic lysine 5,6-aminomutase ( EC ).
- Prokaryotic glutamate mutase ( EC ) [ PUBMED:10467146 ].
- Prokaryotic methyleneglutarate mutase ( EC ).
- Prokaryotic isobutyryl-CoA mutase ( EC ).
The core structure of the cobalamin-binding domain is characterised by a five-stranded alpha/beta (Rossmann) fold, which consists of 5 parallel beta-sheets surrounded by 4-5 alpha helices in three layers (alpha/beta/alpha) [ PUBMED:7992050 ]. Upon binding cobalamin, important elements of the binding site appear to become structured, including an alpha-helix that forms on one side of the cleft accommodating the nucleotide 'tail' of the cofactor. In cobalamin, the cobalt atom can be either free (dmb-off) or bound to dimethylbenzimidazole (dmb-on) according to the pH. When bound to the cobalamin-binding domain, the dimethylbenzimidazole ligand is replaced by the active histidine (His-on) of the DXHXXG motif. The replacement of dimethylbenzimidazole by histidine allows switching between the catalytic and activation cycles [ PUBMED:8805541 ]. In methionine synthase the cobalamin cofactor is sandwiched between the cobalamin-binding domain and an approximately 90 residues N-terminal domain forming a helical bundle comprising two pairs of antiparallel helices [ PUBMED:8805541 ].
In methionine synthase, there is a second, adjacent domain involved in cobalamin binding that forms a 4-helical bundle cap ( INTERPRO ); in the conversion to the active conformation of this enzyme, the 4-helical cap rotates to allow the cobalamin cofactor to bind the activation domain ( INTERPRO ) [ PUBMED:11731805 ].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Molecular function||metal ion binding (GO:0046872)|
|cobalamin binding (GO:0031419)|
Below is a listing of the unique domain organisations or architectures in which this domain is found. More...
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A class of redox enzymes are two domain proteins. One domain, termed the catalytic domain, confers substrate specificity and the precise reaction of the enzyme. The other domain, which is common to this class of redox enzymes, is a Rossmann-fold domain. The Rossmann domain binds nicotinamide adenine dinucleotide (NAD+) and it is this cofactor that reversibly accepts a hydride ion, which is lost or gained by the substrate in the redox reaction. Rossmann domains have an alpha/beta fold, which has a central beta sheet, with approximately five alpha helices found surrounding the beta sheet.The strands forming the beta sheet are found in the following characteristic order 654123. The inter sheet crossover of the stands in the sheet form the NAD+ binding site . In some more distantly relate Rossmann domains the NAD+ cofactor is replaced by the functionally similar cofactor FAD.
The clan contains the following 209 members:2-Hacid_dh_C 3Beta_HSD 3HCDH_N 3HCDH_RFF adh_short adh_short_C2 ADH_zinc_N ADH_zinc_N_2 AdoHcyase_NAD AdoMet_MTase AlaDh_PNT_C Amino_oxidase ApbA AviRa B12-binding Bac_GDH Bin3 Bmt2 BMT5-like BpsA_C CARME CbiJ CheR CMAS CmcI CoA_binding CoA_binding_2 CoA_binding_3 Cons_hypoth95 CoV_ExoN CoV_Methyltr_2 DAO DapB_N DFP DNA_methylase DOT1 DRE2_N DREV DUF1442 DUF1611_N DUF166 DUF1776 DUF268 DUF2855 DUF3410 DUF364 DUF5129 DUF5130 DUF6094 DUF938 DXP_reductoisom DXPR_C Eco57I ELFV_dehydrog Eno-Rase_FAD_bd Eno-Rase_NADH_b Enoyl_reductase Epimerase F420_oxidored FAD_binding_2 FAD_binding_3 FAD_oxidored Fibrillarin FMO-like FmrO FtsJ fvmX7 G6PD_N GCD14 GDI GDP_Man_Dehyd GFO_IDH_MocA GIDA GidB GLF Glu_dehyd_C Glyco_hydro_4 Glyco_tran_WecG GMC_oxred_N Gp_dh_N GRAS GRDA HcgC HI0933_like HIM1 IlvN ISPD_C KR LCM Ldh_1_N LpxI_N Lycopene_cycl Lys_Orn_oxgnase Malic_M Mannitol_dh MCRA Met_10 Methyltr_RsmB-F Methyltr_RsmF_N Methyltrans_Mon Methyltrans_SAM Methyltransf_10 Methyltransf_11 Methyltransf_12 Methyltransf_14 Methyltransf_15 Methyltransf_16 Methyltransf_17 Methyltransf_18 Methyltransf_19 Methyltransf_2 Methyltransf_20 Methyltransf_21 Methyltransf_22 Methyltransf_23 Methyltransf_24 Methyltransf_25 Methyltransf_28 Methyltransf_29 Methyltransf_3 Methyltransf_30 Methyltransf_31 Methyltransf_32 Methyltransf_33 Methyltransf_34 Methyltransf_4 Methyltransf_5 Methyltransf_7 Methyltransf_8 Methyltransf_9 Methyltransf_PK MethyltransfD12 MetW Mg-por_mtran_C MmeI_Mtase MOLO1 Mqo MT-A70 MTS Mur_ligase N6-adenineMlase N6_Mtase N6_N4_Mtase NAD_binding_10 NAD_binding_2 NAD_binding_3 NAD_binding_4 NAD_binding_5 NAD_binding_7 NAD_binding_8 NAD_binding_9 NAD_Gly3P_dh_N NAS NmrA NNMT_PNMT_TEMT NodS OCD_Mu_crystall OpcA_G6PD_assem Orbi_VP4 PALP PARP_regulatory PCMT PDH_N PglD_N Polysacc_syn_2C Polysacc_synt_2 Pox_MCEL Pox_mRNA-cap Prenylcys_lyase PrmA PRMT5 Pyr_redox Pyr_redox_2 Pyr_redox_3 Reovirus_L2 RmlD_sub_bind Rossmann-like rRNA_methylase RrnaAD Rsm22 RsmJ Sacchrp_dh_NADP SAM_MT SE Semialdhyde_dh Shikimate_DH Spermine_synth SRR1 TehB THF_DHG_CYH_C Thi4 ThiF TPM_phosphatase TPMT TrkA_N TRM TRM13 TrmK tRNA_U5-meth_tr Trp_halogenase TylF Ubie_methyltran UDPG_MGDP_dh_N UPF0020 UPF0146 Urocanase V_cholerae_RfbT XdhC_C YjeF_N
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1Cannot generate PP/Heatmap alignments for seeds; no PP data available
Key: available, not generated, — not available.
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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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|Seed source:||Pfam-B_359 (release 5.2)|
|Author:||Bateman A , Mian N|
|Number in seed:||85|
|Number in full:||23984|
|Average length of the domain:||114.70 aa|
|Average identity of full alignment:||23 %|
|Average coverage of the sequence by the domain:||17.01 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||22|
|Download:||download the raw HMM for this family|
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Unmapped species names
The tree is built by looking at each sequence in the full alignment for the family. We take the name of the species given by UniProt and try to map that to the full taxonomic tree from NCBI. In some cases, the name chosen by UniProt does not map to any node in the NCBI tree, perhaps because the chosen name is listed as a synonym or a misspelling in the NCBI taxonomy.
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Since we reduce the species tree to only the eight main taxonomic levels, sequences that are mapped to the sub-species level in the tree would not normally be shown. Rather than leave out these species, we map them instead to their parent species. So, for example, for sequences belonging to one of the Vibrio cholerae sub-species in the NCBI taxonomy, we show them instead as belonging to the species Vibrio cholerae.
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The tree shows the occurrence of this domain across different species. More...
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For all of the domain matches in a full alignment, we count the number that are found on all sequences in the alignment. This total is shown in the purple box.
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Finally, we group sequences from the same organism according to the NCBI code that is assigned by UniProt, allowing us to count the number of distinct sequences on which the domain is found. This value is shown in the pink boxes.
We use the NCBI species tree to group organisms according to their taxonomy and this forms the structure of the displayed tree. Note that in some cases the trees are too large (have too many nodes) to allow us to build an interactive tree, but in most cases you can still view the tree in a plain text, non-interactive representation. Those species which are represented in the seed alignment for this domain are highlighted.
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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 B12-binding domain has been found. There are 105 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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AlphaFold Structure Predictions
The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.