Characterization of the glyoxalases of the malarial parasite Plasmodium falciparum and comparison with their human counterparts.

• The glyoxalase system consisting of glyoxalase I (GloI) and glyoxalase II (GloII) constitutes a glutathione-dependent intracellular pathway converting toxic 2-oxoaldehydes, such as methylglyoxal, to the corresponding 2-hydroxyacids. Here we describe a complete glyoxalase system in the malarial parasite Plasmodium falciparum. The biochemical, kinetic and structural properties of cytosolic GloI (cGloI) and two GloIIs (cytosolic GloII named cGloII, and tGloII preceded by a targeting sequence) were directly compared with the respective isofunctional host enzymes. cGloI and cGloII exhibit lower K(m) values and higher catalytic efficiencies (k(cat)/K(m) ) than the human counterparts, pointing to the importance of the system in malarial parasites. A Tyr185Phe mutant of cGloII shows a 2.5-fold increase in K(m) , proving the contribution of Tyr185 to substrate binding. Molecular models suggest very similar active sites/metal binding sites of parasite and host cell enzymes. However, a fourth protein, which has highest similarities to GloI, was found to be unique for malarial parasites; it is likely to act in the apicoplast, and has as yet undefined substrate specificity. Various S-(N-hydroxy-N-arylcarbamoyl)glutathiones tested as P. falciparum Glo inhibitors were active in the lower nanomolar range. The Glo system of Plasmodium will be further evaluated as a target for the development of antimalarial drugs.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinsk bioteknologi -- Medicinsk bioteknologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Medical Biotechnology -- Medical Biotechnology (hsv//eng)

Nyckelord

Amino Acid Sequence

Animals

Binding Sites

Comparative Study

Gene Expression Regulation

Glutathione/*pharmacology

Humans

Kinetics

Lactoylglutathione Lyase/antagonists & inhibitors/chemistry/genetics

Metals/chemistry

Models; Molecular

Molecular Sequence Data

Plasmodium falciparum/*enzymology

Protein Conformation

Protein Structure; Tertiary

Recombinant Proteins/chemistry/genetics

Research Support; Non-U.S. Gov't

Sequence Alignment

Thiolester Hydrolases/antagonists & inhibitors/chemistry/genetics

Biochemistry

Biokemi

Publikations- och innehållstyp

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