1mvl
From Proteopedia
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| , resolution 2.0Å | |||||||
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| Ligands: | |||||||
| Activity: | Phosphopantothenoylcysteine decarboxylase, with EC number 4.1.1.36 | ||||||
| Related: | 1E20, 1MVN
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
PPC decarboxylase mutant C175S
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
1MVL 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
Page seeded by OCA on Sun Mar 30 22:21:44 2008
