Article

European Biophysics Journal

, Volume 34, Issue 5, pp 469-476

Insight into the self-association of key enzymes from pathogenic species

  • Matthew A. PeruginiAffiliated withDepartment of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne Email author 
  • , Michael D. W. GriffinAffiliated withSchool of Biological Sciences, University of CanterburyNZ Institute of Crop and Food Research Ltd.
  • , Brian J. SmithAffiliated withStructural Biology Division, Walter and Eliza Hall Institute
  • , Lauren E. WebbAffiliated withDepartment of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne
  • , Antony J. DavisAffiliated withInfection and Immunity Division, Walter and Eliza Hall Institute
  • , Emanuela HandmanAffiliated withInfection and Immunity Division, Walter and Eliza Hall Institute
  • , Juliet A. GerrardAffiliated withSchool of Biological Sciences, University of Canterbury

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Abstract

Self-association of protein monomers to higher-order oligomers plays an important role in a plethora of biological phenomena. The classical biophysical technique of analytical ultracentrifugation is a key method used to measure protein oligomerisation. Recent advances in sedimentation data analysis have enabled the effects of diffusion to be deconvoluted from sample heterogeneity, permitting the direct identification of oligomeric species in self-associating systems. Two such systems are described and reviewed in this study. First, we examine the enzyme dihydrodipicolinate synthase (DHDPS), which crystallises as a tetramer. Wild-type DHDPS plays a critical role in lysine biosynthesis in microbes and is therefore an important antibiotic target. To confirm the state of association of DHDPS in solution, we employed sedimentation velocity and sedimentation equilibrium studies in an analytical ultracentrifuge to show that DHDPS exists in a slow dimer–tetramer equilibrium with a dissociation constant of 76 nM. Second, we review works describing the hexamerisation of GDP-mannose pyrophosphorylase (GDP-MP), an enzyme that plays a critical role in mannose metabolism in Leishmania species. Although the structure of the GDP-MP hexamer has not yet been determined, we describe a three-dimensional model of the hexamer based largely on homology with the uridyltransferase enzyme, Glmu. GDP-MP is a novel drug target for the treatment of leishmaniasis, a devastating parasitic disease that infects more than 12 million people worldwide. Given that both GDP-MP and DHDPS are only active in their oligomeric states, we propose that inhibition of the self-association of critical enzymes in disease is an emerging paradigm for therapeutic intervention.

Keywords

Analytical ultracentrifugation Binding Bioinformatics Drug discovery Enzyme Leishmania Protein-protein interactions Sedimentation Structural modeling