1MVL

PPC decarboxylase mutant C175S

Summary for 1MVL

• Entry DOI: 10.2210/pdb1mvl/pdb
• Related: 1E20 1MVN
• Descriptor: PPC decarboxylase AtHAL3a, FLAVIN MONONUCLEOTIDE (3 entities in total)
• Functional Keywords: flavoprotein, ppc decarboxylase, active site mutant c175s, lyase
• Biological source: Arabidopsis thaliana (thale cress)
• Total number of polymer chains: 1
• Total formula weight: 23821.12

Authors

Steinbacher, S.,Hernandez-Acosta, P.,Bieseler, B.,Blaesse, M.,Huber, R.,Culianez-Macia, F.A.,Kupke, T. (deposition date: 2002-09-26, release date: 2003-03-04, Last modification date: 2023-10-25)

Primary citation

Steinbacher, S.,Hernandez-Acosta, P.,Bieseler, B.,Blaesse, M.,Huber, R.,Culianez-Macia, F.A.,Kupke, T.
Crystal Structure of the Plant PPC Decarboxylase AtHAL3a Complexed with an Ene-thiol Reaction Intermediate
J.Mol.Biol., 327:193-202, 2003

PubMed Abstract: 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.

PubMed: 12614618
DOI: 10.1016/S0022-2836(03)00092-5

Experimental method

X-RAY DIFFRACTION (2 Å)