Scientists identify tissue-degrading enzyme in white-nose syndrome

May 4, 2015
A scanning electron micrograph of a dense mass of filamentous Pseudogymnoascus destructans cells (in purple) entangling mouse body hair. Credit: Chapman Beekman and Matt Hirakawa (Brown University).

Scientists at UC San Francisco and Brown University have figured out the likely way that white-nose syn-drome breaks down tissue in bats, opening the door to potential treatments for a disease that has killed more than six million bats since 2006 and poses a threat to the agricultural industry.

In less than 10 years, has spread to 26 states and five provinces in Canada, killing almost all of the in some locations. Scientists say it represents one of the steepest declines in North American wildlife of the last century. It is a particular threat to the , which relies upon bats to control insects. A single bat eats up to 4,500 insects, the equivalent of its body weight, each night.

White-nose syndrome is caused by a fungus—Pseudogymnoascus destructans—which was imported from Europe and thrives in the cold caves where bats hibernate. European bats have adapted to the fungus, but American bats have no defenses, and it breaks down the in their wings while they sleep.

The fungus feeds itself by exporting and then importing the break-down products, in a process called extracellular digestion. To understand the digestive capability of this fungus, the scientists first identified all of the exported enzymes and then isolated the one most likely causing tissue destruc-tion.

They found an enzyme that could digest collagen, which forms the support structure of tissue. They named this enzyme Destructin-1, and searched through the scientific literature to identify inhibitors that could block its action.

They tested one called chymostatin and found that it protected most - about three-quarters - of the colla-gen from being broken down, but not all of it.

"It suggests the fungus is exporting other substances that can degrade collagen," said Richard Bennett, PhD, an associate professor in the Department of Microbiology and Immunology at Brown University.

The group plans to screen other compounds to find more effective blockers of Destructin-1. Their studies, published Monday, May 4, in Proceedings of the National Academy of Sciences, were performed using a commercial source of collagen, but they plan to do more work in bat tissue and to collaborate with re-searchers who work with living bats.

Study IDs collagen-damaging protein in White Nose syndrome
White nose syndrome is a fungal infection that damages collagen in bats. In less than a decade, more than 6 million bats in North America have died from the syndrome. Credit: Ryan von Linden/N.Y. Department of Environmental Conservation

Anthony O'Donoghue, PhD, an associate specialist in the Department of Pharmaceutical Chemistry at UCSF who specializes in studying enzymes, said the technology that made it possible to rapidly identify and then characterize all the protein-degrading enzymes that the fungus exports has only been available for a couple of years. He said the work he did with co-first author Giselle Knudsen, PhD, an assistant professor in the Department of Pharmaceutical Chemistry at UCSF, is the most sophisticated analysis yet of how a fungus destroys tissue.

It's not yet clear whether these findings will be enough to save many bats, some species of which may soon be threatened with extinction if the continues to spread. Bennett said ecologists may have to try a variety of methods to protect bats from further destruction.

"These include ecological approaches for limiting the spread of the pathogen across the US, along with new methods for limiting the infection or supporting bat health," he said.

Explore further: Bacteria inhibit bat-killing fungus, could combat white-nose syndrome

More information: Destructin-1 is a collagen-degrading endopeptidase secreted by Pseudogymnoascus destructans, the causative agent of white-nose syndrome, Proceedings of the National Academy of Sciences, www.pnas.org/cgi/doi/10.1073/pnas.1507082112

Related Stories

Fungus that's killing millions of bats 'isn't going away'

November 5, 2013

University of Illinois researchers say that an infectious and lethal cold-loving fungus that has killed an estimated 6 million bats in North America can persist indefinitely in caves whether there are bats in them or not.

Up to 6.7 million bats dead from fungus: US

January 17, 2012

Between 5.7 and 6.7 million bats have died in North America due to a fungus known as white-nose syndrome (WNS) since the disease first appeared in 2006, US authorities said on Tuesday.

How does white-nose syndrome kill bats?

January 5, 2015

For the first time, scientists have developed a detailed explanation of how white-nose syndrome (WNS) is killing millions of bats in North America, according to a new study by the U.S. Geological Survey and the University ...

Recommended for you

Sea sponges stay put with anchors that bend but don't break

June 22, 2017

Sea sponges known as Venus' flower baskets remain fixed to the sea floor with nothing more than an array of thin, hair-like anchors made essentially of glass. It's an important job, and new research suggests that it's the ...

Custom-built molecule shows promise as anti-cancer therapy

June 22, 2017

Scientists at the University of Bath funded by Cancer Research UK have custom-built a molecule which stops breast cancer cells from multiplying in laboratory trials, and hope it will eventually lead to a treatment for the ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.