Amyloid diseases such as Parkinson’s, Alzheimer’s and type-2 diabetes pose a particular problem for drug designers because they do not present a clear target structure to aim at.
Instead of the disease being linked to a single, easily identifiable species such as the active site of an enzyme or a specific receptor, amyloid diseases are associated with heterogeneous accumulations of proteins sticking together.
This is the key reason why many amyloid diseases are currently incurable.
The new study, published in Nature Chemical Biology, outlines a way of using antibiotic resistance to find chemicals capable of stopping amyloid formation.
She said: “Until now, we haven’t had effective ways to identify drugs to combat amyloid formation. Amyloid-prone proteins often don’t have a clearly defined structure, which makes it very difficult to identify areas to target with drugs.
“Also, because amyloid-causing proteins have a tendency to stick together, they can be very hard to study in the lab. This study shows a way of getting around these problems by grafting amyloid-prone sequences into enzymes which break down antibiotics.”
The study, involving researchers in the University’s School of Chemistry and the Astbury Centre for Structural Molecular Biology, exploits the complex series of adversarial relationships between molecules in a positive way to select for chemicals that counter amyloid formation.
First, amyloid-prone sequences from target proteins are attached to antibiotic degrading beta-lactamase enzymes. Bacteria carrying the modified enzymes are combined in laboratory dishes with the antibiotic. Normally, the presence of the beta-lactamase would disable the antibiotic, allowing bacterial growth.
However, the amyloid-causing sequences act as “Trojan horses” in the beta-lactamase, preventing it from attacking the antibiotic and therefore stopping the tell-tale bacterial growth. Next, the researchers add chemicals and test whether they disable the amyloid-causing sequences, freeing the beta-lactamase to attack the antibiotic and allowing bacterial growth.
Dr Janet Saunders, a researcher on the study,said: “In our research, an old enemy—anti-bacterial resistance—turns out to be our friend. When we see bacterial growth, we know we have chemicals that are obstructing amyloid formation.”
The study identified one chemical—L-dopamine—that blocks amyloid deposits forming from sequences associated with type II diabetes. However, the real significance of the work is its potential for generic use with any protein associated with amyloid disease.
Co-authorDr David Brockwell, Associate Professor in the University’s School of Molecular and Cellular Biology, said: “If you can insert a protein sequence into beta-lactamase, you are likely to be able to use this technique as a screen for chemicals capable of inhibiting its aggregation. You can screen thousands of compounds by putting them through this test.”
Professor Radford said: “It is important to stress that an efficient screen is only one step in the journey toward drug discovery. The power of our study is that it provides the first step on this path by showing us the type of molecules we should be looking at to inhibit a particular disease-causing protein.”
Another application of the new technique could be for use in the manufacture of bio-pharmaceuticals, a class of protein-based drugs that includes many of the highest grossing modern drugs.
Dr Brockwell said: “The problem with many of these new protein-based drugs is that they suffer from similar problems to those we see in amyloid diseases; they stick together. This means you can end up with potentially life-saving drugs that you cannot manufacture.
“We are investigating whether we can use our technique to work out which biopharmaceuticals will be resistant to aggregation and hence much more likely to be successful as a drug product.”
The research was funded through a Biotechnology and Biological Sciences Research Council (BBSRC) industrial CASE partnership with University of Leeds spinout Avacta Group, an AIM-listed company dedicating to providing transformational tools to life scientists.
Innovate UK and the BBSRC have provided additional funding to explore the technique’s use with bio-pharmaceuticals.
The Astbury Centre for Structural Molecular Biology at the University of Leeds is one of Europe’s leading centres for structural biology.
Its research looks at biological structures at an atomic level and is vital to finding new ways to deal with biomedical challenges including ageing, cancer, heart disease and drug resistance.
The centre has a grant portfolio of over £50 million from funders including the Wellcome Trust, the Biotechnology and Biological Sciences Research Council (BBSRC), the Medical Research Council (MRC), the Engineering and Physical Sciences Research Council (EPSRC), the European Research Council (ERC), British Heart Foundation, Cancer Research UK, Yorkshire Cancer Research, and The Bill and Melinda Gates Foundation.
Graham Askew, Simon Walker, BBSRC (Jan 2018), £699,781
Jennifer Tomlinson, Royal Society (Jan 2018), £512,801
Jennifer Tomlinson, Royal Society-Research Fellows Enhancement Award (Dec 2017), £94,681
Helen Miller, AB AGri Grant (Dec 2017), £73,600
Simon Walker, Royal Society Enhancement Award (Dec 2017), £10,000
Carrie Ferguson, Bryan Taylor, Harry Rossiter, The Physiological Society (Dec 2017), £7,392
Ralf Richter, Royal Society (Dec 2017), £6,000
Christine Foyer, British Council Newton Fund (Dec 2017), £49,840
Adrian Whitehouse and colleagues in School of Chemistry and University of Liverpool, MRC (Nov 2017), £622,319
Michelle Peckham, Neil Ransom, MRC (Nov 2017), £495,159
Dave Lewis, British Council India (Nov 2017), £22,540
Elton Zeqiraj, Royal Society (Nov 2017), £15,000
Hannah Dugdale, Royal Society (Nov 2017), £15,000
Shaunna Burke, Cancer Research UK Innovation Grant (Nov 2017), £20,000
Alex O'Neill and colleagues in Chemistry, BBSRC (Nov 2017), £431,865
Jessica Kwok, Wings for Life (Nov 2017), £87,365
Tom Bennett, BBSRC (Oct 2017), £523,679
Neil Ranson, Darren Tomlinson, BBSRC (Oct 2017), £494,318
Nikita Gamper, BBSRC (Oct 2017), £490,426
Amanda Bretman and colleagues from UEA, NERC (Oct 2017), £430,886
Juan Fontana, Rosetrees Trust consumables grant (Oct 2017), £22,500
Helen Miller, DSM Nutritional Products AG (Sep 2017), £69,988
Neil Ranson, Juan Fontana, Mark Harris, Michelle Peckham, Ralf Richter, Peter Stockley, Patricija Van Oosten-Hawle and colleagues in Engineering, FMH and MAPS, Wellcome Trust Equipment Call (Sep 2017), £418,000
Jamie Johnston, Physiological Society (Sep 2017), £10,000
Frank Sobott, Adrian Goldman, Mark Harris, Andrew Macdonald, Stephen Muench, Sheena Radford and colleagues in FMH and MAPS, Wellcome Trust Equipment Call (Aug 2017), £415,000
Ralf Richter, David Brockwell, Eric Hewitt, Jessica Kwok, Emanuele Paci and MAPS/FMH, BBSRC (Jun 2017), £600,000
Eric Blair, Adrian Whitehouse, Nicola Stonehouse, Alison Baker, Richard Bayliss, Joan Boyes, Ryan Seipke, Sally Boxall and MAPS/FMH, BBSRC (Jun 2017), £376,000
Stefan Kepinski, Yoselin Benitez-Alfonso, Tom Bennett, Michelle Peckham, BBSRC (Jun 2017), £331,000
Roman Tuma, Lars Jeuken, Paul Millner, Sheena Radford, Peter Stockley and MAPS/FMH, BBSRC (Jun 2017), £222,000
Vas Ponnambalam, Darren Tomlinson, Stephen Wheatcroft, BHF (May 2017), £107,878
Graham Askew in collaboration with Bangor University, BBSRC (Mar 2017), £477,383
Stephen Muench, BBSRC (Mar 2017), £132,945
Nic Stonehouse, MRC (Mar 2017), £906,341
Bill Kunin, Steve Sait, BBSRC (Mar 2017), £602,831
Adrian Goldman, EU (Mar 2017), £546,576
Sheena Radford, Wellcome Trust (Mar 2017), £1,836,482
Beatrice Filippi, Royal Society (Mar 2017), £15,000
Tom Bennett, Royal Society (Mar 2017), £15,000
Jamie Johnston, Royal Society (Mar 2017), £15,000
Ryan Seipke, BBSRC (Feb 2017), £52,116
Mary O'Connell, BBSRC (Feb 2017), £46,986
Hannah Dugdale, NERC (Feb 2017), £504,138
Anastasia Zhuravleva, EPSRC (Jan 2017), £100,792