Yongkang Xi, Research Fellow for Mechanical Engineering, observes a microscopic image of tardigrade proteins within vesicles at GG Brown on North Campus of the University of Michigan in Ann Arbor, MI
Photo Credit: Jeremy Little, Michigan Engineering
Scientific Frontline: Extended "At a Glance" Summary: Tardigrade CAHS12 Protein and Synthetic Cell Preservation
The Core Concept: The cytoplasmic abundant heat-soluble protein (CAHS12), naturally found in resilient microscopic tardigrades, can be utilized to preserve the structural integrity and biological function of synthetic cells during extreme dehydration. By replicating this natural survival mechanism, scientists can dry out and successfully rehydrate biological materials without causing cellular death.
Key Distinction/Mechanism: While dehydration typically destroys conventional animal cells, the CAHS12 protein reacts to water loss by binding to the fat molecules in the cell membrane. The proteins link together to self-assemble a 3D gel network that physically stabilizes the cell's surface and internal biological machinery. Upon rehydration, this matrix seamlessly dissolves, restoring the cell's normal function.
Major Frameworks/Components:
- CAHS12 Protein: The specific tardigrade-derived protein responsible for forming protective biological structures under environmental stress.
- Coarse-Grained Molecular Dynamics: Computer simulations utilized to mathematically model how the protective gel matrix self-assembles and interacts with the cell membrane during dehydration.
- Dehydration-Rehydration Cycling: The experimental framework proving that synthetic cells equipped with CAHS12 retain complex internal machinery, such as the ability to read DNA and produce fluorescent proteins, post-rehydration.
- Biological Microfactories: Synthetic cellular constructs made of lipids, proteins, and nucleic acids engineered for targeted molecular production.
Branch of Science: Synthetic Biology, Molecular Engineering, Biotechnology, Biochemistry.
Future Application: The engineering of synthetic proteins to preserve medical and biological materials. This will enable the transport of dehydrated biological "microfactories" capable of producing vaccines, medicines, and biosensors directly at the point of use upon the simple addition of water.
Why It Matters: This discovery addresses a major bottleneck in modern biotechnology by eliminating the need for strict refrigeration (the "cold chain") during the transport of fragile biological products. It paves the way for a cheaper, more durable, and globally accessible medical supply chain.
The findings could help make synthetic cells easier and cheaper to store and transport for the point-of-use production of medicines and other useful molecules.
A protein found only in microscopic tardigrades, one that allows them to survive extreme conditions like dehydration, can confer similar durability in synthetic cells, according to new research from the University of Michigan Engineering and the University of Chicago Pritzker School of Molecular Engineering.
The findings could reveal a new way to store and transport biological “microfactories.” Constructed from cell building blocks like lipids, proteins, and nucleic acids, synthetic cells have the potential to produce medicines in less expensive facilities, deliver medicines to specific parts of the body, and detect or consume pollutants in the environment. However, they need to be kept cold when not in use.
“A major bottleneck in modern biotech is that many valuable biological products—things like vaccines, enzymes, cell-free reagents, or biosensors—are fragile and require refrigeration or freezing during transport from factory to end user,” said Yongkang Xi, U-M research fellow in mechanical engineering and co-first author of the study published in Nature Communications. “This work shows a plausible way to change that.”
The study, exploring how synthetic cells could come back from dehydration, was funded by the US Army Research Office and the National Science Foundation.
Tardigrades, or “water bears” as they are often called, are among the most resilient creatures on Earth. When they become dehydrated, protective structures form within their cells to maintain structural integrity. The structures dissolve upon rehydration, allowing the cells to work again. In other animal cells, where this protein is not present, dehydration kills.
One such protein is called cytoplasmic abundant heat-soluble protein (CAHS12). Until now, researchers knew that it was important in preserving tardigrade cells under duress, but they did not know exactly how it worked.
“What we found is that there are particular parts of the proteins that are really important for binding to the cell membrane and other parts that are involved in building the fibrous support system,” said Andrew Ferguson, professor of molecular engineering at UChicago PME and co-corresponding author of the study. “We used molecular modeling to show why CAHS12 causes this protective behavior within synthetic cells and understand which parts of the protein lead to these properties.”
Simulations showed that each CAHS12 protein has parts that are attracted to both the watery cell interior and the fat molecules of the cell membrane. In a hydrated cell, they float freely, but as the cell dries out, the attraction to the membrane begins to dominate. The proteins, gathering and aligning near the membrane, trigger a chain reaction in which they link together, forming a 3D gel network that fills the cell. This stabilizes both the cell’s surface and its delicate interior.
To see whether other cells could take advantage of the same proteins, U-M researchers created synthetic cells containing CAHS12 and subjected them to a dehydration-rehydration process. In this demonstration, the cells contained DNA that encoded a red fluorescent protein and the parts needed to turn those instructions into a red fluorescent signal.
After dehydrating and rehydrating the synthetic cells, the team then tested whether the internal machinery of the cell had survived—namely, had it retained the ability to read DNA and produce proteins? The synthetic cells glowed red under the microscope.
“What we see is that CAHS12 not only protects the membrane but also preserves the internal content, maintaining the biological activity,” said Allen Liu, U-M professor of both mechanical and biomedical engineering and co-corresponding author of the study.
Key insights about how the proteins self-assembled came from computer simulations by co-first author Jianming Mao, a PhD student in chemistry at UChicago. He used coarse-grained molecular dynamics to reveal the gel matrix that supported the cell through dehydration, answering questions about what happens to CAHS12 when it becomes dried out, how long it interacts with the cell membrane, and what those interactions do.
This detailed information will help researchers design synthetic proteins tailored to preserve biological materials, including synthetic cells, through dehydration. Then, when they arrive at the point of use, adding water brings them out of hibernation, just like a tardigrade.
Reference material: What Is: Synthetic Biology
Published in journal: Nature Communications
Title: Cytoplasmic abundant heat-soluble proteins from tardigrades protect synthetic cells under stress
Authors: Yongkang Xi, Jianming Mao, Samuel J. Chen, Hossein Moghimianavval, Young Jin Lee, Ayush Panda, Alexander J. Huang, Daniel H. Zhou, L. Andy Xu, Kayla Y. Fu, Solomon Adera, Andrew L. Ferguson, and Allen P. Liu
Source/Credit: University of Michigan
Reference Number: sybi050626_01
.png)
.jpg)