title: A tetrameric structure is not essential for activity in dihydrodipicolinate synthase (DHDPS) from Mycobacterium tuberculosis.
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 2.1Å) 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.
authors.affiliation: Biomolecular Interaction Centre and School of Biological Sciences, University of Canterbury, Christchurch, New Zealand.
authors.forename: Genevieve
authors.initials: G
authors.lastname: Evans
authors.forename: Linda
authors.initials: L
authors.lastname: Schuldt
authors.forename: Michael D W
authors.initials: MD
authors.lastname: Griffin
authors.forename: Sean R A
authors.initials: SR
authors.lastname: Devenish
authors.forename: F
authors.initials: F
authors.lastname: Grant Pearce
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Perugini
authors.forename: Renwick C J
authors.initials: RC
authors.lastname: Dobson
authors.forename: Geoffrey B
authors.initials: GB
authors.lastname: Jameson
authors.forename: Manfred S
authors.initials: MS
authors.lastname: Weiss
authors.forename: Juliet A
authors.initials: JA
authors.lastname: Gerrard
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D019281:Dimerization; D004795:Enzyme Stability; D006836:Hydro-Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009169:Mycobacterium tuberculosis / Q000201:enzymology* / Q000235:genetics; D015202:Protein Engineering; D054730:Protein Interaction Domains and Motifs; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D006836:Hydro-Lyases; C020040:4-hydroxy-tetrahydrodipicolinate synthase