Arabidopsis thaliana flavoprotein AtHAL3a catalyzes the decarboxylation of 4'-Phosphopantothenoylcysteine to 4'-phosphopantetheine, a key step in coenzyme A biosynthesis.
The Arabidopsis thaliana flavoprotein AtHAL3a is related to plant growth and salt and osmotic tolerance. AtHAL3a shows sequence homology to the bacterial flavoproteins EpiD and Dfp. EpiD, Dfp, and AtHAL3a are members of the homo-oligomeric flavin-containing Cys decarboxylase (HFCD) protein family. We demonstrate that AtHAL3a catalyzes the decarboxylation of (R)-4'-phospho-N-pantothenoylcysteine to 4'-phosphopantetheine. This key step in coenzyme A biosynthesis is catalyzed in bacteria by the Dfp proteins. Exchange of His-90 of AtHAL3a for Asn led to complete inactivation of the enzyme. Dfp and AtHAL3a are characterized by a shortened substrate binding clamp compared with EpiD. Exchange of the cysteine residue of the conserved ACGD motif of this binding clamp resulted in loss of (R)-4'-phospho-N-pantothenoylcysteine decarboxylase activity. Based on the crystal structures of EpiD H67N with bound substrate peptide and of AtHAL3a, we present a model for the binding of (R)-4'-phospho-N-pantothenoylcysteine to AtHAL3a.
Kupke
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Lehrstuhl für Mikrobielle Genetik, Universität Tübingen, Auf der Morgenstelle 15, Verfügungsgebäude, 72076 Tübingen, Germany.
Hernandez-Acosta
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Steinbacher
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Culianez-Macia
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D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000737:chemistry*; D029681:Arabidopsis Proteins; D001665:Binding Sites; D002262:Carboxy-Lyases / Q000737:chemistry; D002384:Catalysis; D002850:Chromatography, Gel; D003065:Coenzyme A / Q000096:biosynthesis*; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010088:Oxidoreductases / Q000737:chemistry; D010204:Pantetheine / Q000031:analogs & derivatives* / Q000378:metabolism*; D010205:Pantothenic Acid / Q000031:analogs & derivatives / Q000378:metabolism*; D010453:Peptide Synthases / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D011487:Protein Conformation; D012492:Salts / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013997:Time Factors
D029681:Arabidopsis Proteins; C404262:AtHAL3 protein, Arabidopsis; D009097:Multienzyme Complexes; D010940:Plant Proteins; D012492:Salts; D010205:Pantothenic Acid; D010204:Pantetheine; C011967:pantothenylcysteine 4'-phosphate; D010088:Oxidoreductases; C075971:epidermin decarboxylase; D002262:Carboxy-Lyases; D010453:Peptide Synthases; D003545:Cysteine; C003129:4'-phosphopantetheine; D003065:Coenzyme A