Molecular Cloning, Expression, Characterization and Mutation of Plasmodium Falciparum Guanylate Kinase

Mol Biochem Parasitol. 2008 Jun;159(2):130-3. doi: 10.1016/j.molbiopara.2008.02.004. Epub 2008 Feb 15.

Abstract

The present work describes cloning, expression, purification, characterization, and mutation of Plasmodium falciparum guanylate kinase (PlasmoDB ID PFI1420w). Amino-acid sequence alignment revealed important differences especially in K42-V51, Y73-A77, and F100-L110, which include residues important for kinase activity, and at helix 3, which is important for domain movements. The catalytic efficiency for dGMP was 22-fold lower than that for GMP, whose value is the lowest among known guanylate kinases. dGMP was found to a competitive inhibitor for GMP with K(i)=0.148 mM and a mixed-type inhibitor with regard to ATP with measured K(i)=0.4 mM. The specificity constant (K(cat)/K(m)) of the four examined mutants varied for natural substrate GMP/dGMP, indicating the involvement of different mechanisms in substrate recognition and subsequent loop-domain movement. These results show that P. falciparum guanylate kinase is structurally and biochemically distinct from other guanylate kinases and could be a possible target in drug development.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Amino Acid Sequence
  • Amino Acid Substitution / genetics
  • Animals
  • Cloning, Molecular
  • DNA Mutational Analysis
  • Deoxyguanine Nucleotides / metabolism
  • Deoxyguanine Nucleotides / pharmacology
  • Enzyme Inhibitors / pharmacology
  • Gene Expression
  • Guanosine Monophosphate / metabolism
  • Guanylate Kinases / genetics*
  • Guanylate Kinases / isolation & purification
  • Guanylate Kinases / metabolism*
  • Kinetics
  • Molecular Sequence Data
  • Mutation, Missense
  • Plasmodium falciparum / enzymology*
  • Plasmodium falciparum / genetics
  • Sequence Alignment

Substances

  • Deoxyguanine Nucleotides
  • Enzyme Inhibitors
  • 2'-deoxyguanosine 5'-phosphate
  • Guanosine Monophosphate
  • Adenosine Triphosphate
  • Guanylate Kinases