Structural and functional characterization of H protein mutants of the glycine decarboxylase complex.

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Gueguen V, Macherel D, Neuburger M, Pierre CS, Jaquinod M, Gans P, Douce R, Bourguignon J

Structural and functional characterization of H protein mutants of the glycine decarboxylase complex.

J Biol Chem. 1999 Sep 10;274(37):26344-52.

PubMed ID

10473591 [ View in PubMed

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Abstract

The mitochondrial glycine decarboxylase complex (GDC) consists of four component enzymes (P, H, T, and L proteins) involved in the breakdown of glycine. In order to investigate structural interactions involved in the stabilization of the methylamine-loaded H protein (a transient species in the GDC reaction), we designed several mutants of H apoprotein. Structural analysis of the wild-type and mutants of H apoprotein emphasized the necessity to carefully assess, by biophysical techniques, the correct folding of mutated proteins prior to investigate their biochemical properties. The correctly folded wild-type and mutants of H apoprotein were in vitro lipoylated and then characterized in the context of GDC reaction by studying the reconstituted complex and partial reactions. We showed that Val(62) and Ala(64), surrounding the lipoyl-lysine, play an important role in the molecular events that govern the reaction between P and H protein but do not intervene in the recognition of the binding site of lipoic acid by lipoyl ligase. The biochemical results obtained with the HE14A mutant of H protein pointed out the major role of the Glu(14) amino acid residue in the GDC catalysis and highlighted the importance of the ionic and hydrogen bounds in the hydrophobic cleft of H protein for the stabilization of the methylamine-loaded lipoyl arm.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Lipoic acid	Lipoyltransferase 1, mitochondrial	Protein	Humans	Unknown	Not Available	Details