1mvl
From Proteopedia
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'''PPC decarboxylase mutant C175S''' | '''PPC decarboxylase mutant C175S''' | ||
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[[Category: Kupke, T.]] | [[Category: Kupke, T.]] | ||
[[Category: Steinbacher, S.]] | [[Category: Steinbacher, S.]] | ||
| - | [[Category: | + | [[Category: Active site mutant c175]] |
| - | [[Category: | + | [[Category: Flavoprotein]] |
| - | [[Category: | + | [[Category: Ppc decarboxylase]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 01:46:25 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 22:46, 2 May 2008
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 Sat May 3 01:46:25 2008
