Summary

Delta-aminolevulinic acid dehydratase

No Pfam abstract.

InterPro entry IPR001731

Tetrapyrroles are large macrocyclic compounds derived from a common biosynthetic pathway PUBMED:16564539. The end-product, uroporphyrinogen III, is used to synthesise a number of important molecules, including vitamin B12, haem, sirohaem, chlorophyll, coenzyme F430 and phytochromobilin PUBMED:17227226.

The first stage in tetrapyrrole synthesis is the synthesis of 5-aminoaevulinic acid ALA via two possible routes: (1) condensation of succinyl CoA and glycine (C4 pathway) using ALA synthase (), or (2) decarboxylation of glutamate (C5 pathway) via three different enzymes, glutamyl-tRNA synthetase () to charge a tRNA with glutamate, glutamyl-tRNA reductase () to reduce glutamyl-tRNA to glutamate-1-semialdehyde (GSA), and GSA aminotransferase () to catalyse a transamination reaction to produce ALA.

The second stage is to convert ALA to uroporphyrinogen III, the first macrocyclic tetrapyrrolic structure in the pathway. This is achieved by the action of three enzymes in one common pathway: porphobilinogen (PBG) synthase (or ALA dehydratase, ) to condense two ALA molecules to generate porphobilinogen; hydroxymethylbilane synthase (or PBG deaminase, ) to polymerise four PBG molecules into preuroporphyrinogen (tetrapyrrole structure); and uroporphyrinogen III synthase () to link two pyrrole units together (rings A and D) to yield uroporphyrinogen III.

Uroporphyrinogen III is the first branch point of the pathway. To synthesise cobalamin (vitamin B12), sirohaem, and coenzyme F430, uroporphyrinogen III needs to be converted into precorrin-2 by the action of uroporphyrinogen III methyltransferase (). To synthesise haem and chlorophyll, uroporphyrinogen III needs to be decarboxylated into coproporphyrinogen III by the action of uroporphyrinogen III decarboxylase () PUBMED:11215515.

This entry represents porphobilinogen (PBG) synthase (PBGS, or 5-aminoaevulinic acid dehydratase, or ALAD, ), which functions during the second stage of tetrapyrrole biosynthesis. This enzyme catalyses a Knorr-type condensation reaction between two molecules of ALA to generate porphobilinogen, the pyrrolic building block used in later steps PUBMED:17311232. The structure of the enzyme is based on a TIM barrel topology made up of eight identical subunits, where each subunit binds to a metal ion that is essential for activity, usually zinc (in yeast, mammals and certain bacteria) or magnesium (in plants and other bacteria). A lysine has been implicated in the catalytic mechanism PUBMED:3092810. The lack of PBGS enzyme causes a rare porphyric disorder known as ALAD porphyria, which appears to involve conformational changes in the enzyme PUBMED:17236137.

Clan

This family is a member of clan TIM_barrel (CL0036), which contains the following 54 members:

Ala_racemase_N ALAD Aldolase AP_endonuc_2 BtpA CdhD CutC DAHP_synth_1 DeoC DHDPS DHO_dh DHquinase_I DUF1341 DUF556 DUF561 DUF692 DUF993 Dus F_bP_aldolase FMN_dh G3P_antiterm Glu_syn_central Glu_synthase His_biosynth HMGL-like IGPS IMPDH iPGM_N MtrH NanE NAPRTase NeuB NPD OMPdecase Orn_Arg_deC_N Oxidored_FMN PcrB PdxJ PhosphMutase PRAI Pterin_bind QRPTase_C RhaA Ribul_P_3_epim SOR_SNZ Tagatose_6_P_K ThiG TIM TIM-br_sig_trns TMP-TENI Transaldolase Trp_syntA UvdE UxuA

Gene Ontology

Molecular function	metal ion binding (GO:0046872)
Molecular function	porphobilinogen synthase activity (GO:0004655)
Biological process	tetrapyrrole biosynthetic process (GO:0033014)

Internal database links

SCOOP:

DUF1462

External database links

HOMSTRAD:	ALAD
PANDIT:	PF00490
PROSITE:	PDOC00153
SCOP:	1aw5
SYSTERS:	ALAD

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Alignments

There are various ways to view or download the sequence alignments that we store. You can use a sequence viewer to look at either the seed or full alignment for the family, or you can look at a plain text version of the sequence in a variety of different formats. More...

View options

Alignment:	Seed (165) Full (1510) NCBI (3944) Metagenomics (2727)
Viewer:

Formatting options

Alignment:	Seed (165) Full (1510)
Format:
Order:	Tree Alphabetical
Sequence:	Inserts lower case All upper case
Gaps:
Download/view:	Download View

Download options

Very large alignments can often cause problems for the formatting tool above. If you find that downloading or viewing a large alignment is problematic, you can also download a gzip-compressed, Stockholm-format file containing the seed or full alignment for this family.

You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

The main seed and full alignments are generated using sequences from the UniProt sequence database. However, we also generate alignments using sequences from the NCBI sequence database and the "metaseq" metagenomics dataset.

You can view alignments from these two additional datasets using the form above, or you can download alignments of NCBI or metagenomics sequences, as gzip-compressed files.

Pfam alignments:	Seed (165) Full (1510) NCBI (3944) Metagenomics (2727)
Full length sequences	Full-sequences (1510)

External links

MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER2.

HMM logo

HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...

Trees

This page displays the phylogenetic tree for this family. 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 or full alignments.

Note: You can also download the data files for the seed, full, NCBI or metagenomics trees.

Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation

Seed source:

Prosite

Previous IDs:

none

Type:

Domain

Author:

Finn RD, Griffiths-Jones SR

Number in seed:

165

Number in full:

1510

Average length of the domain:

313.50 aa

Average identity of full alignment:

48 %

Average coverage of the sequence by the domain:

95.40 %

HMM information

HMM build commands:

build method: hmmbuild -o /dev/null HMM SEED

search method: hmmsearch -Z 9421015 -E 1000 HMM pfamseq

Model details:

Parameter	Sequence	Domain
Gathering cut-off	20.6	20.6
Trusted cut-off	21.2	31.6
Noise cut-off	20.4	20.5

Model length:

324

Family (HMM) version:

14

Download:

download the raw HMM for this family

Species distribution

Tree controls

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The tree shows the occurrence of this domain across different species. More...

Species trees

We show the species tree in one of two ways. For smaller trees we try to show an interactive representation, which allows you to select specific nodes in the tree and view them as an alignment or as a set of Pfam domain graphics.

Unfortunately we have found that there are problems viewing the interactive tree when the it becomes larger than a certain limit. Furthermore, we have found that Internet Explorer can become unresponsive when viewing some trees, regardless of their size. We therefore show a text representation of the species tree when the size is above a certain limit or if you are using Internet Explorer to view the site.

If you are using IE you can still load the interactive tree by clicking the "Generate interactive tree" button, but please be aware of the potential problems that the interactive species tree can cause.

Interactive tree

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.

We also count the number of unique sequences on which each domain is found, which is shown in green. Note that a domain may appear multiple times on the same sequence, leading to the difference between these two numbers.

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.

You can use the tree controls to manipulate how the interactive tree is displayed:

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highlight species that are represented in the seed alignment
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Interactions

There is 1 interaction for this family. More...

ALAD

Structures

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 ALAD domain has been found.

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Family: ALAD (PF00490)

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