A truly collaborative work – new paper on DsbA

Not one but five CFBD members from our three nodes published a paper on DsbA titled “Identification and characterization of two drug-like fragments that bind to the same cryptic binding pocket of Burkholderia pseudomallei DsbA” in Acta Crystallographica Section D.

Abstract

Disulfide-bond-forming proteins (Dsbs) play a crucial role in the pathogenicity of many Gram-negative bacteria. Disulfide-bond-forming protein A (DsbA) catalyzes the formation of the disulfide bonds necessary for the activity and stability of multiple substrate proteins, including many virulence factors. Hence, DsbA is an attractive target for the development of new drugs to combat bacterial infections. Here, two fragments, bromophenoxy propanamide (1) and 4-methoxy-N-phenylbenzenesulfonamide (2), were identified that bind to DsbA from the pathogenic bacterium Burkholderia pseudomallei, the causative agent of melioidosis. The crystal structures of oxidized B. pseudomallei DsbA (termed BpsDsbA) co-crystallized with 1 or 2 show that both fragments bind to a hydrophobic pocket that is formed by a change in the side-chain orientation of Tyr110. This conformational change opens a `cryptic’ pocket that is not evident in the apoprotein structure. This binding location was supported by 2D-NMR studies, which identified a chemical shift perturbation of the Tyr110 backbone amide resonance of more than 0.05 p.p.m. upon the addition of 2 mM fragment 1 and of more than 0.04 p.p.m. upon the addition of 1 mM fragment 2. Although binding was detected by both X-ray crystallography and NMR, the binding affinity (Kd) for both fragments was low (above 2 mM), suggesting weak interactions with BpsDsbA. This conclusion is also supported by the crystal structure models, which ascribe partial occupancy to the ligands in the cryptic binding pocket. Small fragments such as 1 and 2 are not expected to have a high energetic binding affinity due to their relatively small surface area and the few functional groups that are available for intermolecular interactions. However, their simplicity makes them ideal for functionalization and optimization. The identification of the binding sites of 1 and 2 to BpsDsbA could provide a starting point for the development of more potent novel antimicrobial compounds that target DsbA and bacterial virulence.

Read the full article here.

First Author paper for PhD student Sarah Müller

Congratulations to PhD student Sarah Müller from Griffith University who published a paper as first author. 

The Glitazone Class of Drugs as Carbonic Anhydrase Inhibitors—A Spin-Off Discovery from Fragment Screening

Most of the drugs we know target the activity of specific proteins that play an important role in the disease being treated. One of the big challenges in the discovery of new drugs is finding molecules that bind specifically to one target and not bind to other proteins too. This is necessary to avoid causing treatment side effects. Hence, drug discovery researchers are always on the lookout for ways to find better lead molecules.
We identified an old drug class called glitazones that target a new protein known as carbonic anhydrase II, an enzyme that helps to maintain pH levels in cells. Carbonic anhydrase comes in many different forms and has been a successful target for drug development for various diseases like glaucoma, heart failure and epilepsy.
The glitazone drugs, such as rosiglitazone, are used to treat Type II diabetes. However, because of the severe side effects caused by the use of glitazones they were taken off the market. Our findings suggest that the unintended targeting of carbonic anhydrase may be one reason for the side effects of these drugs. This shows how important it is to carry out research to fully understand the effect of drugs and can help future researchers in drug discovery.

The paper was published in Molecules in May 2021.

ARC Discovery Project Success

Congratulations to CFBD CI Professor Sally-Ann Poulsen from Griffith University for being awarded an ARC Discovery Project grant worth $415,495 together with Professor Katherine Andrews (Griffith Institute for Drug Discovery, Sciences). The project Chemical probes to dissect the cell cycle of globally important parasites aims to develop new reagents, called chemical probes, to visualise key biological events in globally important pathogens. The team will use innovative chemistry to modify the building blocks of DNA and provide researchers with essential tools to ‘see’ DNA synthesis in order to study growth and replication of pathogens in combination with microscopy. This project expects to support a major technical advance that will address important gaps in our understanding of many pathogens (e.g. those that cause malaria and tuberculosis), at both the cellular and molecular levels. This should provide significant benefits by enabling researchers worldwide to identify new intervention opportunities that target unique aspects of pathogen biology (with Dr Martin Blume, Robert Koch Institute).

Celebrating the official launch of ARC CFBD

Dr Narelle Tunstall, Centre Manager

The Centre for Fragment-Based Design officially commenced on 22 July 2019 with the execution of our Participants Agreement and the Centre was launched by The Honourable Kevin Andrews MP on 12 November 2019. The launch was held in conjunction with Australia’s national conference on Fragment-Based Drug Design, which allowed us to leverage a full week of activities including our first Scientific Advisory Board meeting and the Centre’s first training events, in partnership with key industry and international stakeholders. 

The launch, conference and training workshops were very well received by attendees, with many of our academic and industry participants and other stakeholders in attendance. These initial activities have established a strong base of interest in the Centre for further collaborative opportunities that will drive our research initiatives and support growth, productivity and competitiveness in fragment-based design for the sector.

There was some great coverage of the event. Monash and Griffith both had media releases publicising the launch event, which were picked up by a Universities to Business article.

Our partners GE Healthcare (now Cytiva) had a number of representatives, including Paul Belcher all the way from Boston, who wrote a great LinkedIn article about the event.

Dan Erlanson wrote a great summary article on his Practical Fragments blog.

Our objective to establish a coherent and collaborative national network to provide access to the technology necessary to support fragment screening against a wide range of protein targets, has now been firmly grounded in the established Centre. We now have a strong platform and clear means to implement our training program activities, accelerate research translation and continue to engage with industry to meet the growing needs within the rapidly moving sector. 

Professor Martin Scanlon explaining the aims of the ARC CFBD to The Honourable Kevin Andrews MP, the Monash Provost (Professor Marc Parlange), MIPS Director (Professor Chris Porter), Monash DVCR (Professor Rebekah Brown) and ARC CEO (Professor Sue Thomas).
Centre Director, Professor Martin Scanlon speaking about the Centre’s research program and industry partnerships following the unveiling of the plaque.

Feature image: Centre CIs (L-R: Professor Jonathan Baell, Professor Sally-Ann Poulsen, Professor Michael Kassiou, Professor Joel Mackay, Dr Maria Halili, Professor Martin Scanlon and Professor Ray Norton) with ARC CEO Professor Sue Thomas and Centre Manager Dr Narelle Tunstall.