Get   for     ? 
 Site search     ? 
Catalytic Site Atlas Version 2.2.12
Find Annotated Site: PDB code:
Swiss-Prot code:
EC number:
Help
CSA entry for 1mvn
Original Entry
Title:
Lyase
Compound:
Ppc decarboxylase athal3a
Mutant:
Yes
UniProt/Swiss-Prot:
Q9SWE5-HL3A_ARATH
EC Class:
4.1.1.36
Other CSA Entries:
Overview of all sites for 1mvn
Homologues of 1mvn
Entries for UniProt/Swiss-Prot: Q9SWE5
Entries for EC: 4.1.1.36
Other Databases:
PDB entry: 1mvn
PDBsum entry: 1mvn
UniProt/Swiss-Prot: Q9SWE5
IntEnz entry: 4.1.1.36
Literature Report:
Introduction:
The Arabidopsis thaliana flavoprotein AtHAL3a catalyses the oxidative decarboxylation of 4'-phosphopantothenoylcysteine to 4'-phosphopantetheine, a step in coenzyme A biosynthesis. It belongs to the family of homo-oligomeric flavin-containing cysteine decarboxylases (HFCD) family.
Mechanism:
The mechanism involves 2 reaction steps:oxidative decarboxylation to form a thioaldehyde intermediate and the reduction of the intermediate. First, a thiolate ion is stabilised by His90, which acts as a base to deprotonate the thio-group of the substrate cysteine. Electrons are transferred by an SET mechanism from the thiolate to FMN together with the deprotonation of the beta-carbon of the substrate cysteine by His90. This results in a thioaldehyde intermediate which decarboxylates spontaneously, forming a cis ene-thiolate. The ene-thiolate is then reduced by direct hydride transfer from FMNH2 to the beta-carbon atom and the concomitant protonation of the alpha-carbon by Cys175.
Sites:

Click to Display Catalytic Site (Get help with this section)
Found by:
Literature reference 

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
1002 0
Electron donor/acceptorSubstrate
It is a cofactor involved in the hydride transfer, firstly deprotonating the thiolate ion to oxidise it to form a thioaldehyde intermediate and secondly protonating to reduce the cis enethiolate intermediate to form the product.
Evidence from paper Evidence concerns Evidence type
PubMed ID 12614618 Current protein Structural similarity to homologue of known mechanism

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
HISA 90 90Sidechain
Acid/baseSubstrate
It acts as a base to deprotonate the thio-group of the substrate cysteine to form a thiolate ion.
Evidence from paper Evidence concerns Evidence type
PubMed ID 11279129 Current protein Mutagenesis of residue
PubMed ID 11279129 Current protein Conservation of residue

ResidueChainNumberUniProt numberFunctional part FunctionTargetDescription
SERA 175 175Sidechain
Acid/baseSubstrate
It acts as an acid to deprotonate the alpha-carbon atom in the cis ene-thiolate intermediate, concomitant to the hydride transfer from FMNH2 to the beta-carbon atom, in the reduction of the intermediate.
Evidence from paper Evidence concerns Evidence type
PubMed ID 12614618 Current protein Mutagenesis of residue
PubMed ID 12614618 Current protein Structural similarity to homologue of known mechanism
References:
1
Arabidopsis thaliana flavoprotein AtHAL3a catalyzes the decarboxylation of 4'-Phosphopantothenoylcysteine to 4'-phosphopantetheine, a key step in coenzyme A biosynthesis.
T. Kupke and P. Hernandez-Acosta and S. Steinbacher and F. A. Culianez-Macia
J Biol Chem 276, (22) 19190-6, (2001).
11279129
2
Crystal structure of the plant PPC decarboxylase AtHAL3a complexed with an ene-thiol reaction intermediate.
S. Steinbacher and P. Hernández-Acosta and B. Bieseler and M. Blaesse and R. Huber and F. A. Culiáñez-Macià and T. Kupke
J Mol Biol 327, (1) 193-202, (2003).
12614618
Which EBI biological databases are available and how do I access them? EBI Site Map