Enhancing allosteric inhibition of dihydrodipicolinate synthase through the design and synthesis of novel dimeric compounds

The synthesis of the first dimeric inhibitor of E. coli dihydrodipicolinate synthase (DHDPS) is reported herein. Inspired by 2,4-thiazolidinedione based ligands previously shown to inhibit DHDPS, a series of dimeric inhibitors were designed and synthesised, incorporating various alkyl chain bridges between two 2,4-thiazolidinedione moieties. Aiming to exploit the multimeric nature of this enzyme and enhance potency, a dimeric compound with a single methylene bridge achieved the desired outcome with low micromolar inhibition of E. coli DHDPS observed. This work highlights the continued importance of investigation into DHDPS as an antibacterial target. Furthermore, we demonstrate the design of dimeric ligands can provide a promising strategy to improve potency in the search for novel bioactive compounds.</p

The fragment-based development of a benzofuran hit as a new class of Escherichia coli DsbA inhibitors

A fragment-based drug discovery approach was taken to target the thiol-disulfide oxidoreductase enzyme DsbA from Escherichia coli (EcDsbA). This enzyme is critical for the correct folding of virulence factors in many pathogenic Gram-negative bacteria, and small molecule inhibitors can potentially be developed as anti-virulence compounds. Biophysical screening of a library of fragments identified several classes of fragments with affinity to EcDsbA. One hit with high mM affinity, 2-(6-bromobenzofuran-3-yl)acetic acid (6), was chemically elaborated at several positions around the scaffold. X-ray crystal structures of the elaborated analogues showed binding in the hydrophobic binding groove adjacent to the catalytic disulfide bond of EcDsbA. Binding affinity was calculated based on NMR studies and compounds 25 and 28 were identified as the highest affinity binders with dissociation constants (KD) of 326 ± 25 and 341 ± 57 µM respectively. This work suggests the potential to develop benzofuran fragments into a novel class of EcDsbA inhibitors.</p

A dual-target herbicidal inhibitor of lysine biosynthesis

Herbicides with novel modes of action are urgently needed to safeguard global agricultural industries against the damaging effects of herbicide-resistant weeds. We recently developed the first herbicidal inhibitors of lysine biosynthesis, which provided proof-of-concept for a promising novel herbicide target. In this study, we expanded upon our understanding of the mode of action of herbicidal lysine biosynthesis inhibitors. We previously postulated that these inhibitors may act as proherbicides. Here, we show this is not the case. We report an additional mode of action of these inhibitors, through their inhibition of a second lysine biosynthesis enzyme, and investigate the molecular determinants of inhibition. Furthermore, we extend our herbicidal activity analyses to include a weed species of global significance.</p

Elaboration of a Benzofuran Scaffold and Evaluation of Binding Affinity and Inhibition of Escherichia coli DsbA: A Fragment-Based Drug Design Approach to Novel Antivirulence Compounds

Bacterial thiol-disulfide oxidoreductase DsbA is essential for bacterial virulence factor assembly and has been identified as a viable antivirulence target. Herein, we report a structure-based elaboration of a benzofuran hit that bound to the active site groove of Escherichia coli DsbA. Substituted phenyl groups were installed at the 5- and 6-position of the benzofuran using Suzuki-Miyaura coupling. HSQC NMR titration experiments showed dissociation constants of this series in the high µM to low mM range and X-ray crystallography produced three co-structures, showing binding in the hydrophobic groove, comparable with that of the previously reported benzofurans. The 6-(m-methoxy)phenyl analogue (2b), which showed a promising binding pose, was chosen for elaboration from the C-2 position. The 2,6-disubstituted analogues bound to the hydrophobic region of the binding groove and the C-2 groups extended into the more polar, previously un-probed, region of the binding groove. Biochemical analysis of the 2,6-disubsituted analogues showed they inhibited DsbA oxidation activity in vitro. The results indicate the potential to develop the elaborated benzofuran series into a novel class of antivirulence compounds.</p

Elaboration of a Benzofuran Scaffold and Evaluation of Binding Affinity and Inhibition of Escherichia coli DsbA: A Fragment-Based Drug Design Approach to Novel Antivirulence Compounds

No description supplied.</p

Towards novel herbicide modes of action by inhibiting lysine biosynthesis in plants

Weeds are becoming increasingly resistant to our current herbicides, posing a significant threat to agricultural production. Therefore, new herbicides with novel modes of action are urgently needed. In this study, we exploited a novel herbicide target, dihydrodipicolinate synthase (DHDPS), which catalyses the first and rate-limiting step in lysine biosynthesis. The first class of plant DHDPS inhibitors with micromolar potency against Arabidopsis thaliana DHDPS were identified using a high throughput chemical screen. We determined that this class of inhibitors binds to a novel and unexplored pocket within DHDPS, which is highly conserved across plant species. The inhibitors also attenuated the germination and growth of A. thaliana seedlings and confirmed their pre-emergence herbicidal activity in soil-grown plants. These results provide proof-of-concept that lysine biosynthesis represents a promising target for the development of herbicides with a novel mode of action to tackle the global rise of herbicide resistant weeds

A novel small molecule inhibitor of human Drp1

Mitochondrial dynamin-related protein 1 (Drp1) is a large GTPase regulator of mitochondrial dynamics and is known to play an important role in numerous pathophysiological processes. Despite being the most widely used Drp1 inhibitor, the specificity of Mdivi-1 towards human Drp1 has not been definitively proven and there have been numerous issues reported with its use including off-target effects. In our hands Mdivi-1 showed varying binding affinities toward human Drp1, potentially impacted by compound aggregation. Herein, we sought to identify a novel small molecule inhibitor of Drp1. From an initial virtual screening, we identified DRP1i27 as a compound which directly bound to the human isoform 3 of Drp1 via surface plasmon resonance and microscale thermophoresis. Importantly, DRP1i27 was found to have a dose-dependent increase in the cellular networks of fused mitochondria but had no effect in Drp1 knock-out cells. Further analogues of this compound were identified and screened, though none displayed greater affinity to human Drp1 isoform 3 than DRP1i27. To date, this is the first small molecule inhibitor shown to directly bind to human Drp1