Throughout 2024-2025, Research Manitoba celebrates our 10th anniversary year. As we mark this achievement, we will be looking back at some of our past funded researchers to highlight their success.
- Primary Institution: University of Saskatchewan
- Secondary Institution: University of Manitoba
- Program: CFI Matching Funds – Innovation Fund
- Year: 2015
- Project Title: Micro-beam capability for macromoledular crystallography at the CLS
“Research Manitoba was instrumental in launching my research career when I joined the University of Manitoba. The funding I received from them early in my career played a major role in my ability to establish a nationally competitive research program, and ultimately to the research described in this article.
Research Manitoba also funded several studentships and postdoctoral fellowships to support trainees in my laboratory over the years, which helped launch their careers as well.
Research Manitoba plays a pivotal role in ensuring Manitoba scientists and their trainees have the support they need to carry out world-class research.” – Brian Mark
Picture this: Structural biologist Brian Mark is using sophisticated imaging techniques like X-ray crystallography to help tackle potentially fatal diseases
Profile written by: Brian Cole
The image on the computer screen looks an awful lot like a dish of fusilli and fettuccine.
But don’t be fooled, a plate of pasta this is not.
Rather, it is a 3D model of a microscopic protein from a human cell, one that was produced by scientist Brian Mark through a method called X-ray crystallography.
A structural biologist at the University of Manitoba, Mark uses images like the ones accompanying this story to better understand the biochemistry of living organisms at the molecular level, including the interaction of proteins within a human cell.
As he explains, the proteins in a cell are not unlike the parts in a car engine, in that they are organized to fulfill specific purposes.
“The structure of a car engine dictates how it functions,” says Mark, who is also Dean of Science, Microbiology at the university. “Proteins are no different. Their shape and their arrangement, and the chemistry that results from that arrangement and structure, dictates what proteins do in the cell, and so you can gain a ton of knowledge about how human cells work by understanding the three-dimensional structure of proteins that are involved in their creation and maintenance.”
The images below have played a key role in an ongoing effort to develop a potential treatment for Tay-Sachs and Sandhoff diseases, two rare genetic disorders that are caused by a build-up in the brain and nervous system of a fatty substance known as GM2 ganglioside.
Left: rendering of human enzyme, beta-hexosaminidase (ß-HexA).
Right: engineered version of enzyme, HexM.
HexM is more stable and active than HexA, making it more suitable for use in treating patients with Tay-Sachs and Sandhoff diseases.
The green strands in the HexM image represent the backbone structure of the enzyme, whereas the coloured spheres are areas of the enzyme that were engineered to improve its stability. The purple sticks are the regions of the enzyme that carry out the chemistry needed to facilitate the treatment.
As Mark explains, this substance is ordinarily regulated by an enzyme called beta-hexosaminidase A (ß-HexA) – which is encoded by two genes – hexosaminidase A (HEXA) and hexosaminidase B (HEXB).
But on rare occasions, an infant may inherit a HEXA or HEXB gene from both parents that is unable to encode the enzyme needed to degrade GM2 ganglioside. When this happens, the fatty substance can accumulate to toxic levels in infants which can lead to death before the age of four.
Mark’s interest in the biochemistry of the human ß-HexA enzyme – and the disorders that occur when it is not working correctly – can be traced back to when he was a PhD student at the University of Alberta in 2003. But that interest became more focused about six years ago when he received a phone call from Dr. Don Mahuran, a scientist and colleague at the Toronto Hospital for Sick Kids who had been investigating potential treatments for Tay-Sachs and Sandhoff diseases for much of his career.
During the ensuing conversation, Mahuran, posed a question to Mark: Would it be possible to combine the best features of the HEXA and HEXB genes to create a new gene that would then produce an enzyme that would better regulate the toxic build-up of GM2 ganglioside?
In other words, could enzyme replacement therapy be a potential solution for Tay-Sachs and Sandhoff diseases?
Intrigued by the possibilities, Mark agreed to investigate. Turns out the answer was yes. After a few years of work in the lab, Mark and Mahuran created an engineered gene that produces a unique version of the ß-HexA enzyme that is more robust and more stable than the original one. And that new enzyme, known as HexM, has shown promise when tested in mouse-model experiments.
“It significantly extended the life span of mice with Sandhoff disease” says Mark, whose work over the years has been supported by Research Manitoba and other national research funding agencies.
Nonetheless, more work will be needed to refine the treatment and enhance its effectiveness for use in humans.
To that end, Mark and Mahuran have patented the gene sequence used to create the new and improved ß-HexA enzyme. Mark is also working with Barbara Triggs-Raine, a fellow scientist at the U of M, and an American pharmaceutical company to enhance the effectiveness of the treatment. And a non-profit out of Minneapolis called New Hope Research Foundation has licensed HexM for future clinical trial studies.
Eventually, Mark hopes the work now underway will lead to a better, more effective treatment for Tay-Sachs and Sandhoff diseases, one that will ultimately lead to a human clinical trial in the not too distant future.
But Mark’s research is not limited to genetic disorders. He has also spent years studying the biochemistry of viruses, particularly coronaviruses.
In 2020, for example, he was part of a research team that explored ways to prevent the deadly COVID-19 virus from replicating inside the human body.
As Mark explains, COVID-19, like all other coronaviruses, expresses an enzyme, known as a protease, which helps the virus replicate inside the human body. In addition, proteases from some viruses, including COVID-19, also target a protein in the body called ubiquitin, which plays a role in triggering an immune response to an infection.
“So these viruses have evolved in a way to circumvent (the immune response) by removing ubiquitin from other proteins… that activate the immune response.”
The good news is that one of Mark’s collaborators, Sachdev Sidhu at the University of Toronto, has built a biological library of ubiquitin variants that can block the activity of these proteases. And, as luck would have it, they managed to identify one that worked against coronaviruses.
“In this case, we (could) take the coronavirus protease, search the library, and find a ubiquitin protein that basically acts as a potent inhibitor… and when you express the variant in a host cell the ability of the virus to replicate just plummets,” he says. “We’ve shown that for MERS coronavirus, we’ve shown it for SARS II coronavirus.”
Unfortunately, there is a snag.
“The remaining problem, however, is that you cannot just take that ubiquitin and give it to someone as a pill or inject it into them because the proteins cannot get into the cell (that is infected) to block replication. So, as a therapeutic in (humans) it is kind of limited.”
Fortunately, the story doesn’t end there. Mark had a hunch that what would not work in humans might work in plants, so he carried out more research to test his theory.
Repurposing a potential human treatment for plants may seem counterintuitive. But Mark says that underneath the surface, the biochemistry of plants and animals is actually quite similar.
“It doesn’t seem that obvious – plants and animals seem so different. But the biochemistry of plants and animals share common mechanisms that we can target,” he says.
And when he carried out his research?
“I found that there are numerous plant viruses that also express similar types of proteases,” he says. “So we have taken a ubiquitin variant that blocks the replication of a particular plant virus and… we have found that the plant, when they express this ubiquitin variant, the replication of the virus is consistently, statistically, lower than it is without the protein present.”
A paper outlining the research is currently under revision for publication.
Looking forward, Mark says scientists working today in the field of microbiology are just scratching the surface of what may be possible in terms of preventing and treating illness and disease.
“The 19th century was the century of chemistry. The 20th century was the century of physics. The 21st century is going to be the century of biotechnology and biology. All the fundamentals were laid in the late 20th century and now all the tools are becoming so advanced. I think the clinical therapies that arise from that work are going to be pretty remarkable.” – Brian Mark, 2025.
—
Dr. Brian Mark
Dr. Brian Mark is a Professor of Microbiology and a Professor of Biochemistry and Medical Genetics at the University of Manitoba (UM). In addition to his professorships, Dr. Mark is currently the Dean of Science at UM (since 2021) and formerly served as the Associate Dean of Research in the Faculty of Science (2018-2021). Dr. Mark received his PhD in Biochemistry from the University of Alberta in 2003, where he was awarded the Governor General’s gold medal for his PhD work on the structural biology of glycolytic enzymes. He was then a CIHR postdoctoral fellow at Los Alamos National Laboratory (2003-2005) where he studied the structural genomics of Mycobacterium tuberculosis. He joined the UM Department of Microbiology as an Assistant Professor in 2005 and was awarded a Manitoba Research Chair in Pathogen Virulence Mechanisms (2011-2016). Dr. Mark has become internationally recognized for his work on the structural biology of viral proteases and their role in host immune evasion, bacterial antibiotic drug resistance mechanisms, and human lysosomal storage disorders. Working with national and international collaborators from academia and industry, Dr. Mark has published over 60 research articles on these subjects, many appearing in internationally renowned journals. Several articles have been Editors Picks, one highlighted on the homepage of Molecular Therapy and another publicized in the press by the American Society for Microbiology. His most prominent work describes how proteases from several groups of viruses act as deubiquitinases to suppress host immune responses. He has secured over $18 million in external research funding from federal (CIHR, NSERC, CFI), provincial (Research Manitoba) and non-profit (Cystic Fibrosis Foundation) granting agencies, as well as from private industry. He holds 2 patents, and one licensed technology based on his research.