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74  structures 6622  species 0  interactions 8384  sequences 67  architectures

Family: FolB (PF02152)

Summary: Dihydroneopterin aldolase

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This is the Wikipedia entry entitled "Dihydroneopterin aldolase". More...

Dihydroneopterin aldolase Edit Wikipedia article

dihydroneopterin aldolase
EC number4.1.2.25
CAS number37290-59-8
IntEnzIntEnz view
ExPASyNiceZyme view
MetaCycmetabolic pathway
PDB structuresRCSB PDB PDBe PDBsum
Gene OntologyAmiGO / QuickGO
Dihydroneopterin aldolase
PDB 1sql EBI.jpg
crystal structure of 7,8-dihydroneopterin aldolase in complex with guanine
Pfam clanCL0334

In enzymology, a dihydroneopterin aldolase (EC is an enzyme that catalyzes the chemical reaction

2-amino-4-hydroxy-6-(D-erythro-1,2,3-trihydroxypropyl)-7,8- dihydropteridine 2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine + glycolaldehyde

Thus, the substrate (biochemistry) of this enzyme is 2-amino-4-hydroxy-6-(D-erythro-1,2,3-trihydroxypropyl)-7,8-dihydropteridine, whereas its two products are 2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine and glycolaldehyde.

This enzyme belongs to the family of lyases, specifically the aldehyde-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is 2-amino-4-hydroxy-6-(D-erythro-1,2,3-trihydroxypropyl)-7,8-dihydropt eridine glycolaldehyde-lyase (2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine-forming). Other names in common use include 2-amino-4-hydroxy-6-(D-erythro-1,2,3-trihydroxypropyl)-7,8-, and dihydropteridine glycolaldehyde-lyase. This enzyme participates in folate biosynthesis.

Structural studies

As of late 2007, 13 structures have been solved for this class of enzymes, with PDB accession codes 1NBU, 1RRI, 1RRW, 1RRY, 1RS2, 1RS4, 1RSD, 1RSI, 1U68, 1Z9W, 2CG8, 2NM2, and 2NM3.


  • Mathis JB, Brown GM (1970). "The biosynthesis of folic acid. XI. Purification and properties of dihydroneopterin aldolase". J. Biol. Chem. 245 (11): 3015–25. PMID 4912541.

External links

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.

Dihydroneopterin aldolase Provide feedback

This enzyme EC: catalyses the conversion of 7,8-dihydroneopterin to 6-hydroxymethyl-7,8-dihydropterin in the biosynthetic pathway of tetrahydrofolate.

Literature references

  1. Haussmann C, Rohdich F, Schmidt E, Bacher A, Richter G; , J Biol Chem 1998;273:17418-17424.: Biosynthesis of pteridines in Escherichia coli. Structural and mechanistic similarity of dihydroneopterin-triphosphate epimerase and dihydroneopterin aldolase. PUBMED:9651328 EPMC:9651328

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR006157

Dihydroneopterin aldolase (DHNA or folB) catalyses the conversion of 7,8-dihydroneopterin to 6-hydroxymethyl-7,8-dihydropterin in the biosynthetic pathway of tetrahydrofolate [ PUBMED:12039964 ]. Folate derivatives are essential cofactors in the biosynthesis of purines, pyrimidines, and amino acids, as well as formyl-tRNA. Mammalian cells are able to utilize pre-formed folates after uptake by a carrier-mediated active transport system. Most microbes and plants lack this system and must synthesize folates de novo from guanosine triphosphate and DHNA is one enzyme in this pathway. In the opportunistic pathogen Pneumocystis carinii, dihydroneopterin aldolase function is expressed as the N-terminal portion of the multifunctional folic acid synthesis protein (Fas). This region encompasses two domains, FasA and FasB, which are 27% amino acid identical [ PUBMED:9709001 ]. FasA and FasB also share significant amino acid sequence similarity with bacterial dihydroneopterin aldolases.

This entry also includes 7,8-dihydroneopterin triphosphate epimerase domain (DHNTPE or folX). Though it is known that DHNTPE catalyzes the epimerization of dihydroneopterin triphosphate to dihydromonapterin triphosphate, the biological role of this enzyme is still unclear. It is hypothesized that it is not an essential protein since a folX knockout in E. coli has a normal phenotype and the fact that folX is not present in H. influenza [ PUBMED:9182560 , PUBMED:9006053 ]. DHNA and DHNTPE have been shown to be able to compensate for the other's activity albeit at slower reaction rates [ PUBMED:9651328 ]. The functional enzyme for both is an octamer of identical subunits. Mammals lack many of the enzymes in the folate pathway including, DHNA and DHNTPE.

This region consists of two tandem sequences each homologous to folB and which form tetramers [ PUBMED:10737935 ].

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

Domain organisation

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Pfam Clan

This family is a member of clan THBO-biosyn (CL0334), which has the following description:

The families in this clan bind purine or ptein in topologically similar sites between subunits.

The clan contains the following 7 members:

FolB GCHY-1 GTP_cyclohydroI PTPS QueF QueF_N Uricase


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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Seed source: PSI-BLAST P31055
Previous IDs: none
Type: Domain
Sequence Ontology: SO:0000417
Author: Bateman A
Number in seed: 796
Number in full: 8384
Average length of the domain: 110.60 aa
Average identity of full alignment: 27 %
Average coverage of the sequence by the domain: 60.65 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 57096847 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 31.8 31.8
Trusted cut-off 32.1 31.8
Noise cut-off 31.1 31.7
Model length: 111
Family (HMM) version: 20
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Species distribution

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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 FolB domain has been found. There are 74 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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