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Insights in Enzyme Research
ISSN: 2573-4466
E u r o S c i C o n C o n g r e s s o n
Enzymology and
Molecular Biology
A u g u s t 1 3 - 1 4 , 2 0 1 8
P a r i s , F r a n c e
Enzymology 2018
T
he cell wall of Gram-negative bacteria consists of peptidoglycan chains linked together by oligopeptidic sequences comprised
of the amino acids L-Ala, D-Ala, D-Glu and meso-diaminopimelate (DAP). Meso-DAP is synthesised via the DAP pathway
that also yields the basic amino acid, L-lysine. Gene knock-out studies show that enzymes functioning in the DAP pathway
are essential to bacteria, including dihydrodipicolinate synthase (DHDPS). DHDPS is an allosteric enzyme that catalyses the
first-committed and rate-limiting step in DAP biosynthesis. It forms a homo-tetrameric structure that gives rise to at least two
‘druggable’ sites, namely (a) the active site and (b) the allosteric site, which binds lysine to mediate a feedback inhibition response.
Given its essentiality to bacteria and absence in humans, DHDPS represents a valid but as yet unchartered target for antimicrobial
development. Recently, we have developed two classes of small molecule inhibitors that target the DHDPS active site and allosteric
site using a contemporary multi-disciplinary workflow spanning biophysics, biochemistry, medicinal chemistry, microbiology
and structural biology. Inhibition studies in combination with biophysical techniques have demonstrated that these compounds
are broad-spectrum inhibitors of bacterial DHDPS
in vitro
, representing the most potent DHDPS inhibitors discovered to date.
Using viability and time-kill assays, these inhibitors have been shown to be bactericidal against both drug-sensitive and drug-
resistant strains of Gram-negative bacteria (MIC= 8 – 64 μg/ml), including
Acinetobacter baumannii, Pseudomonas aeruginosa
and Escherichia coli
, but are non-toxic to cultured human cells at >1028 μg/ml. Importantly, these compounds have been shown
to synergise with FDA-approved classes of antibiotics, including β-lactams, fluoroquinolones, rifampicin and aminoglycosides.
This study illustrates the potential for DHDPS inhibitors to be developed into a new class of antimicrobials with excellent potential
to be combined with current antibiotics to yield innovative multi-targeted formulations to minimise the emergence of resistance
.
T.SoaresdaCosta@latrobe.edu.auMulti-targeted inhibition of an essential
bacterial enzyme
Tatiana P Soares da Costa
1
, Chamodi K Gardhi
1
,
Rebecca Christoff
2
, J Mark Sutton
2
, Belinda M Abbott
1
and Matthew A Perugini
1
1
La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria, Australia
3
Public Health England, Salisbury, Wiltshire,UK
Insights Enzyme Res 2018, Volume 2
DOI: 10.21767/2573-4466-C1-003