Summary: Cys/Met metabolism PLP-dependent enzyme
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Cys/Met metabolism PLP-dependent enzyme family Edit Wikipedia article
cystathionine beta-lyase (cbl) from escherichia coli in complex with n-hydrazinocarbonylmethyl-2-trifluoromethyl-benzamide
In molecular biology, the Cys/Met metabolism PLP-dependent enzyme family is a family of proteins including enzymes involved in cysteine and methionine metabolism which use PLP (pyridoxal-5'-phosphate) as a cofactor.
Mechanism of action
PLP is employed as it binds to amino groups and stabilises carbanion intermediates. PLP enzymes exist in their resting state as a Schiff base, the aldehyde group of PLP forming a linkage with the epsilon-amino group of an active site lysine residue on the enzyme. The alpha-amino group of the substrate displaces the lysine epsilon-amino group, in the process forming a new aldimine with the substrate. This aldimine is the common central intermediate for all PLP-catalysed reactions, enzymatic and non-enzymatic.
PLP is the active form of vitamin B6 (pyridoxine or pyridoxal). PLP is a versatile catalyst, acting as a coenzyme in a multitude of reactions, including decarboxylation, deamination and transamination.
A number of pyridoxal-dependent enzymes involved in the metabolism of cysteine, homocysteine and methionine have been shown to be evolutionary related. These enzymes are tetrameric proteins of about 400 amino-acid residues. Each monomer has an active site, which however requires the N-terminal of another monomer to be completed (salt bridges to phosphate and entrance way). The phosphopyridoxyl group is attached to a lysine residue located in the central section of these enzymes and is stabilised by π-stacking interactions with a tyrosine residue above it.
There are five different structurally related types of PLP enzymes. Members of this family belong to the type I and are:
- in the transsulfurylation route for methionine biosynthesis:
- Cystathionine γ-synthase (metB) which joins an activated homoserine ether (acetyl or succinyl) with cysteine to form cystathionine
- Cystathionine β-lyase (metC) which splits cystathionine into homocysteine and a deaminated alanine (pyruvate and ammonia)
- in the direct sulfurylation pathway for methionine biosynthesis:
- O-acetyl homoserine sulfhydrylase (metY) which adds a thiol group to an activated homoserine ether
- O-succinylhomoserine sulfhydrylase (metZ) which adds a thiol group to an activated homoserine ether
- in the reverse transsulfurylation pathway for cysteine biosynthesis:
- Cystathionine γ-lyase (no common gene name) which joins an activated serine ether (acetyl or succinyl) with homocysteine to form cystathionine
- Not Cystathionine β-synthase which is a PLP enzyme type II
- cysteine biosynthesis from serine:
- O-acetyl serine sulfhydrylase (cysK or cysM) which adds a thiol group to an activated serine ether
- methionine degradation:
- Methionine gamma-lyase (mdeA) which breaks down methionine at the thioether and amine bounds
Note: MetC, metB, metZ are closely related and have fuzzy boundaries so fall under the same NCBI orthologue cluster (COG0626).
- Ferla MP, Patrick WM (2014). "Bacterial methionine biosynthesis". Microbiology. 160 (Pt 8): 1571–84. doi:10.1099/mic.0.077826-0. PMID 24939187.
- Toney MD (January 2005). "Reaction specificity in pyridoxal phosphate enzymes". Arch. Biochem. Biophys. 433 (1): 279–87. doi:10.1016/j.abb.2004.09.037. PMID 15581583.
- Hayashi H (September 1995). "Pyridoxal enzymes: mechanistic diversity and uniformity". J. Biochem. 118 (3): 463–73. PMID 8690703.
- John RA (April 1995). "Pyridoxal phosphate-dependent enzymes". Biochim. Biophys. Acta. 1248 (2): 81–96. doi:10.1016/0167-4838(95)00025-p. PMID 7748903.
- Eliot AC, Kirsch JF (2004). "Pyridoxal phosphate enzymes: mechanistic, structural, and evolutionary considerations". Annu. Rev. Biochem. 73: 383–415. doi:10.1146/annurev.biochem.73.011303.074021. PMID 15189147.
- Aitken SM, Lodha PH, Morneau DJ (2011). "The enzymes of the transsulfuration pathways: Active-site characterizations". Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics. 1814 (11): 1511–7. doi:10.1016/j.bbapap.2011.03.006. PMID 21435402.
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.
Cys/Met metabolism PLP-dependent enzyme Provide feedback
This family includes enzymes involved in cysteine and methionine metabolism. The following are members: Cystathionine gamma-lyase, Cystathionine gamma-synthase, Cystathionine beta-lyase, Methionine gamma-lyase, OAH/OAS sulfhydrylase, O-succinylhomoserine sulfhydrylase All of these members participate is slightly different reactions. All these enzymes use PLP (pyridoxal-5'-phosphate) as a cofactor.
Clausen T, Huber R, Laber B, Pohlenz HD, Messerschmidt A; , J Mol Biol 1996;262:202-224.: Crystal structure of the pyridoxal-5'-phosphate dependent cystathionine beta-lyase from Escherichia coli at 1.83 A. PUBMED:8831789 EPMC:8831789
Internal database links
|SCOOP:||Alliinase_C Aminotran_1_2 Aminotran_3 Aminotran_5 Asp_aminotransf Beta_elim_lyase DegT_DnrJ_EryC1 GDC-P Met_gamma_lyase OKR_DC_1 Pyridoxal_deC SelA SepSecS SHMT|
|Similarity to PfamA using HHSearch:||Aminotran_1_2 Aminotran_5 DegT_DnrJ_EryC1 Beta_elim_lyase SelA Met_gamma_lyase|
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR000277
Pyridoxal phosphate is the active form of vitamin B6 (pyridoxine or pyridoxal). Pyridoxal 5'-phosphate (PLP) is a versatile catalyst, acting as a coenzyme in a multitude of reactions, including decarboxylation, deamination and transamination [ PUBMED:8690703 , PUBMED:7748903 , PUBMED:15189147 ]. PLP-dependent enzymes are primarily involved in the biosynthesis of amino acids and amino acid-derived metabolites, but they are also found in the biosynthetic pathways of amino sugars and in the synthesis or catabolism of neurotransmitters; pyridoxal phosphate can also inhibit DNA polymerases and several steroid receptors [ PUBMED:17109392 ]. Inadequate levels of pyridoxal phosphate in the brain can cause neurological dysfunction, particularly epilepsy [ PUBMED:16763894 ].
PLP enzymes exist in their resting state as a Schiff base, the aldehyde group of PLP forming a linkage with the epsilon-amino group of an active site lysine residue on the enzyme. The alpha-amino group of the substrate displaces the lysine epsilon-amino group, in the process forming a new aldimine with the substrate. This aldimine is the common central intermediate for all PLP-catalysed reactions, enzymatic and non-enzymatic [ PUBMED:15581583 ].
A number of pyridoxal-dependent enzymes involved in the metabolism of cysteine, homocysteine and methionine have been shown [ PUBMED:1577698 , PUBMED:8511966 ] to be evolutionary related. These enzymes are proteins of about 400 amino-acid residues. The pyridoxal-P group is attached to a lysine residue located in the central section of these enzymes.
One of these enzymes is the sulfhydrylase FUB7 from fungi such as Gibberella and Fusarium. The gene is part of a cluster that mediates the biosynthesis of fusaric acid, a mycotoxin with low to moderate toxicity to animals and humans, but with high phytotoxic properties [ PUBMED:26662839 ].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Molecular function||pyridoxal phosphate binding (GO:0030170)|
|Biological process||transsulfuration (GO:0019346)|
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This superfamily contains a variety of PLP-dependent enzymes.
The clan contains the following 16 members:Alliinase_C Aminotran_1_2 Aminotran_3 Aminotran_5 Asp_aminotransf Beta_elim_lyase ComK Cys_Met_Meta_PP DegT_DnrJ_EryC1 GDC-P Met_gamma_lyase OKR_DC_1 Pyridoxal_deC SelA SepSecS SHMT
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|Seed source:||Pfam-B_366 (release 3.0)|
|Author:||Finn RD , Bateman A|
|Number in seed:||25|
|Number in full:||30567|
|Average length of the domain:||366.70 aa|
|Average identity of full alignment:||33 %|
|Average coverage of the sequence by the domain:||89.65 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 57096847 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||22|
|Download:||download the raw HMM for this family|
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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 Cys_Met_Meta_PP domain has been found. There are 373 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.