1mvn | pdb_00001mvn
PPC decarboxylase mutant C175S complexed with pantothenoylaminoethenethiol
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| 1mvn, resolution 2.21Å | |||||||||||||
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| Ligands: | PCO and FMN | ||||||||||||
| Activity: | Phosphopantothenoylcysteine decarboxylase, with EC number 4.1.1.36 | ||||||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||||||
Overview
The Arabidopsis thaliana protein AtHAL3a decarboxylates 4'-phosphopantothenoylcysteine to 4'-phosphopantetheine, a step in coenzyme A biosynthesis. Surprisingly, this decarboxylation reaction is carried out as an FMN-dependent redox reaction. In the first half-reaction, the side-chain of the cysteine residue of 4'-phosphopantothenoylcysteine is oxidised and the thioaldehyde intermediate decarboxylates spontaneously to the 4'-phosphopantothenoyl-aminoethenethiol intermediate. In the second half-reaction this compound is reduced to 4'-phosphopantetheine and the FMNH(2) cofactor is re-oxidised. The active site mutant C175S is unable to perform this reductive half-reaction. Here, we present the crystal structure of the AtHAL3a mutant C175S in complex with the reaction intermediate pantothenoyl-aminoethenethiol and FMNH(2). The geometry of binding suggests that reduction of the C(alpha)=C(beta) double bond of the intermediate can be performed by direct hydride-transfer from N5 of FMNH(2) to C(beta) of the aminoethenethiol-moiety supported by a protonation of C(alpha) by Cys175. The binding mode of the substrate is very similar to that previously observed for a pentapeptide to the homologous enzyme EpiD that introduces the aminoethenethiol-moiety as final reaction product at the C terminus of peptidyl-cysteine residues. This finding further supports our view that these homologous enzymes form a protein family of homo-oligomeric flavin-containing cysteine decarboxylases, which we have termed HFCD family.
About this Structure
1MVN is a Single protein structure of sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA.
Reference
Crystal structure of the plant PPC decarboxylase AtHAL3a complexed with an ene-thiol reaction intermediate., Steinbacher S, Hernandez-Acosta P, Bieseler B, Blaesse M, Huber R, Culianez-Macia FA, Kupke T, J Mol Biol. 2003 Mar 14;327(1):193-202. PMID:12614618
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Proteopedia Page Contributors and Editors (what is this?)
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- Arabidopsis thaliana
- Phosphopantothenoylcysteine decarboxylase
- Single protein
- Bieseler, B.
- Blaesse, M.
- Culianez-Macia, F A.
- Hernandez-Acosta, P.
- Huber, R.
- Kupke, T.
- Steinbacher, S.
- FMN
- PCO
- Active site mutant c175
- Complexed with ene-thiol reaction intermediate
- Flavoprotein
- Ppc decarboxylase
