Acidianus hospitalis Filamentous Virus 1 lives in the bubbling pools of acid of Yellowstone National Park. Researchers from the Institut Pasteur and the University of Virginia School of Medicine have unlocked the secrets of its membrane, which appears to be almost indestructible. This lipid envelope is so unusual it constitutes a third and new type of membrane envelope – only two types had been identified until now.
Acidianus hospitalis Filamentous Virus 1 was discovered in the hot springs of Yellowstone National Park in 20031 by David Prangishvili, a researcher from the Molecular Biology of the Gene in Extremophiles Unit at the Institut Pasteur. Temperatures often exceed 85°C in the park's bubbling pools. "This virus is therefore very resistant and capable of surviving in adverse conditions," explains David Prangishvili. "It literally lives in bubbling acid and survives in very low pH environments [around pH 2]."
The scientist's latest research, carried out with colleagues from the University of Virginia, has determined the structure of this new virus, which is not only found in Yellowstone, but more generally in active volcanic areas, such as southern Italy (close to Naples), Japan and Iceland. "To understand how this type of virus is able to resist such extreme conditions, we needed to analyze its structure at atomic level, continues the scientist. Recent technological advances, particularly in cryo-electron microscopy, have led us to discover that the virus is protected by a type of membrane that has never been seen before."
All living cells, as well as many viruses, are enclosed in a lipid-containing envelope. Two types are known but this one is completely new – "The outer envelope of the virus is half as thick as known cell membranes but it is surprisingly stable." Why is this? Because the membrane lipids are arranged in a horseshoe shape! "This conformation reduces envelope thickness and offers remarkable durability. We have already obtained membranes of this kind in the lab in the past. Now we know that they exist in nature."
As scientists can already reproduce this envelope in the lab, they think it could be used to create a solid material. All sorts of applications are possible in the long term, and in fields from materials science to construction or even medicine. In nanomedicine, such an envelope could be used to stabilize the microscopic particles in drugs so that they can be delivered precisely where needed in the patient's body.
This research received backing from the US National Institutes of Health and the French National Research Agency.
1. Bettstetter M, Peng X, Garrett RA, and Prangishvili D. AFV1, a novel virus infecting hyperthermophilic archaea of the genus Acidianus. Virology 2003. 315:68-79.
Conformational dynamics of 20 lipids from the simulated AFV1 envelope (frames are at nanosecond intervals). Source : https://doi.org/10.7554/eLife.26268.008
Model for a novel membrane envelope in a filamentous hyperthermophilic virus, eLife, June 22, 2017.
Peter Kasson1,2, Frank DiMaio3, Xiong Yu4, Soizick Lucas-Staat5, Mart Krupovic5, Stefan Schouten6,7, David Prangishvili5, Edward H Egelman4
1. Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, United States
2. Department of Biomedical Engineering, University of Virginia, Charlottesville, United States
3. Department of Biochemistry, University of Washington, Seattle, United States
4. Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, United States
5. Department of Microbiology, Institut Pasteur, Paris, France
6. NIOZ Royal Netherlands Institute for Sea Research, Texel, Netherlands
7. Department of Marine Microbiology and Biogeochemistry, Utrecht University, Texel, Netherlands