Crystal Structure of the Plant PPC Decarboxylase AtHAL3a Complexed with an Ene-thiol Reaction IntermediateSteinbacher, S., Hernandez-Acosta, P., Bieseler, B., Blaesse, M., Huber, R., Culianez-Macia, F.A., Kupke, T.
(2003) J.Mol.Biol. 327: 193-202
- PubMed: 12614618
- Primary Citation of Related Structures:  1MVN
- PubMed Abstract:
- Arabidopsis thaliana AtHal3: a flavoprotein related to salt and osmotic tolerance and plant growth
Espinosa-Ruiz, A.,Belles, J.M.,Serrano, R.,Culianez-Macia, F.A.
(1999) Plant J. 20: 529
- Molecular characterization of the Arabidopsis thaliana flavoprotein AtHAL3a reveals the general reaction mechanism of 4'-phosphopantothenoylcysteine decarboxylases
Hernandez-Acosta, P.,Schmid, D.G.,Jung, G.,Culianez-Macia, F.A.,Kupke, T.
(2002) J.Biol.Chem. 277: 20490
- Arabidopsis thaliana flavoprotein AtHAL3a catalyzes the decarboxylation of 4'-phosphopantothenoylcysteine to 4'-phosphopantetheine, a key step in coenzyme A biosynthesis
Kupke, T.,Hernandez-Acosta, P.,Steinbacher, S.,Culianez-Macia, F.A.
(2001) J.Biol.Chem. 276: 19190
- The X-ray structure of the FMN-binding protein AtHal3 provides the structural basis for the activity of a regulatory subunit involved in signal transduction
Albert, A.,Martinez-Ripoll, M.,Espinosa-Ruiz, A.,Yenush, L.,Culianez-Macia, F.A.,Serrano, R.
(2000) Structure 8: 961
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 ...
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.
Max-Planck-Institut für Biochemie, Abteilung für Strukturforschung, Am Klopferspitz 18a, D-82152 Martinsried, Germany. firstname.lastname@example.org