A tetrameric structure is not essential for activity in dihydrodipicolinate synthase (DHDPS) from Mycobacterium tuberculosis |
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| Authors: | Genevieve Evans Linda Schuldt Michael DW Griffin Sean RA Devenish F Grant Pearce Matthew A Perugini Renwick CJ Dobson Geoffrey B Jameson Manfred S Weiss Juliet A Gerrard |
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| Institution: | aBiomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8020, New Zealand;bMaurice Wilkins Centre for Molecular Biodiscovery and School of Biological Sciences, University of Auckland, 3 Symonds Street, Auckland 1142, New Zealand;cEMBL Hamburg Outstation, c/o DESY, Notkestr. 85, D-22603 Hamburg, Germany;dPUMPKIN – Centre for Membrane Pumps in Cells and Disease, Department of Molecular Biology, Aarhus University, Gustav Wieds Vej 10c, DK-8000 Aarhus C, Denmark;eHelmholtz-Zentrum Berlin, Macromolecular Crystallography, BESSY-MX, Albert-Einstein-Str. 15, D-12489 Berlin, Germany;fDepartment of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, 30 Flemington Road, University of Melbourne, Melbourne, Victoria 3010, Australia;gDepartment of Biochemistry, University of Cambridge, Cambridge, United Kingdom;hCentre for Structural Biology, Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand |
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| Abstract: | Dihydrodipicolinate synthase (DHDPS) is a validated antibiotic target for which a new approach to inhibitor design has been proposed: disrupting native tetramer formation by targeting the dimer–dimer interface. In this study, rational design afforded a variant of Mycobacterium tuberculosis, Mtb-DHDPS-A204R, with disrupted quaternary structure. X-ray crystallography (at a resolution of 2.1 Å) revealed a dimeric protein with an identical fold and active-site structure to the tetrameric wild-type enzyme. Analytical ultracentrifugation confirmed the dimeric structure in solution, yet the dimeric mutant has similar activity to the wild-type enzyme. Although the affinity for both substrates was somewhat decreased, the high catalytic competency of the enzyme was surprising in the light of previous results showing that dimeric variants of the Escherichia coli and Bacillus anthracis DHDPS enzymes have dramatically reduced activity compared to their wild-type tetrameric counterparts. These results suggest that Mtb-DHDPS-A204R is similar to the natively dimeric enzyme from Staphylococcus aureus, and highlight our incomplete understanding of the role played by oligomerisation in relating protein structure and function. |
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| Keywords: | DHDPS Dihydrodipicolinate synthase Quaternary structure Tuberculosis |
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