A deeper vision

19 April 2024

Antibiotic resistance. Infectious disease. Muscle function. Cancer. And that’s just the start. When Professor James Whisstock, of the Ramaciotti Centre for cryo-Electron Microscopy, bought a Titan KRIOS cryo-electron microscope 10 years ago, it was the most powerful of its kind dedicated to life science in Australia. And what happened next exceeded everyone’s expectations.

Image (from L-R): Professor John Carroll (Monash University), Professor James Whisstock (Monash University), Craig Connelly (Perpetual), Caitriona Fay (Perpetual)

Monash University researchers, and scientists across Australia and internationally, are now able to use the Ramaciotti Centre microscope to see deeper into living organisms than was ever thought possible. They can study large biological molecules – that have proven impossible to visualise through conventional imaging approaches – at atomic resolution and within the cellular environment, opening extraordinary new research frontiers across the medical world.

The resolution revolution

“High resolution cryo-electron microscopy is the most disruptive technique to enter the structural biology community since the 1950s,” says Professor Whisstock. And the Ramaciotti Centre has been at the forefront of that disruption, ever since a groundbreaking microscope’s purchase courtesy of a $1 million grant from the Clive & Vera Ramaciotti Foundation.

Without that original gift, says Professor Whisstock, none of this would have been possible.

“That million dollars from Ramaciotti seeded everything.”

The original Titan KRIOS is still going strong today but has been joined by another even more powerful sister instrument – the Titan G4. Funded in part through the National Collaborative Research Infrastructure Strategy and Microscopy Australia, the new Titan further represents a cornerstone of Australia’s national microscopy infrastructure.

Electron microscopes work by using a focused beam of electrons – rather than visible light – to scan and image an item. Electrons have a much smaller wavelength than light, so this technique provides much higher resolution imaging.

Cryo-electron microscopes image samples that have been preserved through a process called vitrification. This involves flash-freezing the sample in such a way that it prevents ice crystals, which might otherwise damage the fragile biological structures, from forming. This process also preserves the molecule of interest in-situ, which is what makes cryo-electron microscopy so valuable in the field of both cell biology and structural biology.

For individual proteins, cryo-electron microscopy images multiple copies of a protein from multiple angles, then uses powerful computers to combine those thousands of images into one incredibly detailed three-dimensional image of that protein. “In addition to visualising individual proteins at atomic resolution outside the cell, now we can start to see them in the context of the cell they’re operating in,” Professor Whisstock says.

Disrupting cancer

Neurofibromin, or NF1, is one of the proteins that has had its close-up with the Centre’s suite of cryo-electron microscopes, through the work of Associate Professor Andrew Ellisdon at the Monash Biomedicine Discovery Institute. NF1 has long been of interest to scientists because of the role its mutated forms play in a variety of cancers, including breast, melanoma, brain and lung cancer, as well as a cancer that particularly affects children and young adults, called neurofibromatosis.

Using cryo-electron microscopy, Ellisdon and colleagues have been able to study how neurofibromin acts as a scaffold for many signalling factors within a cell that instruct the cell to grow or divide. This means a mutation affecting neurofibromin has the potential to seriously disrupt those signals, possibly leading to unchecked cell growth and tumour formation.

“Now we have the NF1 structure, we can start to explain the consequences of every single mutation that’s ever been associated with NF1 disease,” says Professor Whisstock, “and then we can ask the question: ‘How can we intervene?’”

Regulating the immune system

Professor Whisstock’s own work looks at a class of proteins called perforin-like proteins, which play a fundamental role in enabling the immune system to kill pathogens, virally infected cells and malignant cells. When uncontrolled, immune cells can release perforin and damage healthy tissue. Using cryo-electron microscopy, Professor Whisstock and his team are studying the mechanism of perforin function, because “if you can understand how something functions, you can also develop approaches to control it”.

A researcher’s super-power

The availability of such powerful microscopes at the Ramaciotti Centre has attracted a new generation of researchers from Monash and across Australia to conduct research using electron microscopy. “What I find really satisfying is that all of these other people – who have never performed a microscopy experiment before – are now coming and using the facility for their research,” says Professor Whisstock.

With cryo-electron microscopy still a relatively new technology, biomedical science may really only have scratched the surface in terms of what it will be able to deliver. “Diseases and conditions that we currently do not understand will become treatable, because of the understanding of structural and cellular biology that arises through direct and high-resolution observation of their components,” he says. “I think that in the next decade we will be able to see cells at near-atomic resolution, and that is going to change the world.”