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3-Methylglutaconyl-CoA hydratase from Acinetobacter sp
Matthias Mack1, Michael Liesert, Johannes Zschocke
1Institut für Technische Mikrobiologie, Fachhochschule Mannheim, Hochschule für Technik und Gestaltung, Windeckstr. 110, 68163, Mannheim, Germany. m.mack@hs-mannheim.de
Archives of Microbiology
|February 17, 2006
Summary
Acinetobacter strain IVS-B utilizes isovalerate for growth, facilitated by 3-methylglutaconyl-CoA hydratase. This enzyme is crucial for the oxidative leucine degradation pathway, converting intermediates into essential compounds.
Area of Science:
- Biochemistry
- Microbiology
- Enzymology
Background:
- Acinetobacter strain IVS-B utilizes isovalerate as its sole carbon and energy source.
- Isovalerate metabolism involves isovaleryl-CoA, an intermediate in the oxidative (S)-leucine degradation pathway.
Purpose of the Study:
- To purify and characterize the 3-methylglutaconyl-CoA hydratase enzyme from Acinetobacter strain IVS-B.
- To elucidate the physiological role of this enzyme in the context of leucine metabolism.
Main Methods:
- Enzyme purification from cell-free extracts of isovalerate-grown Acinetobacter strain IVS-B.
- Enzyme characterization including subunit composition, molecular weight, and cofactor analysis.
- Enzyme kinetic studies using various substrates, including glutaconyl-CoA and 3-methylglutaconyl-CoA.
Main Results:
- A homotetrameric 3-methylglutaconyl-CoA hydratase (115.2 kDa) was purified.
- The enzyme efficiently catalyzes the hydration of (E)-glutaconyl-CoA and dehydration of (S)-3-hydroxyglutaryl-CoA.
- Higher catalytic efficiency was observed for 3-methylglutaconyl-CoA and (S)-3-hydroxy-3-methylglutaryl-CoA, indicating its role in leucine degradation.
Conclusions:
- The enzyme's primary physiological role is the hydration of (E)-3-methylglutaconyl-CoA to (S)-3-hydroxy-3-methylglutaryl-CoA in the leucine degradation pathway.
- The purified enzyme is a homotetramer composed of identical subunits and does not require cofactors.
- Sequence homology suggests related enoyl-CoA hydratases in other prokaryotes may also function as 3-methylglutaconyl-CoA hydratases.