1. Insight into the self-association of key enzymes from pathogenic species.
- Author
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Perugini MA, Griffin MD, Smith BJ, Webb LE, Davis AJ, Handman E, and Gerrard JA
- Subjects
- Animals, Computational Biology methods, Dimerization, Escherichia coli enzymology, Guanosine Diphosphate chemistry, Hydro-Lyases chemistry, Lysine chemistry, Models, Molecular, Nucleotidyltransferases chemistry, Protein Binding, Protein Conformation, Protein Structure, Quaternary, Protein Structure, Tertiary, Pseudomonas aeruginosa enzymology, Software, Streptococcus pneumoniae enzymology, Ultracentrifugation, Biophysics methods, Enzymes chemistry, Leishmania enzymology
- 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.
- Published
- 2005
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