February 26, 2024

Nature’s Nano-Syringes: Harnessing Bacterial Machines for Next-Gen Medicine

Configured Photorhabdus virulence cassettes bound to a cancer cell, imaged with transmission electron microscopy. Credit: Joseph Kreitz/Broad Institute, McGovern Institute
” This is a truly gorgeous example of how protein engineering can modify the biological activity of a natural system,” stated Joseph Kreitz, the studys very first author and a college student in Zhangs lab. “I think it substantiates protein engineering as an useful tool in bioengineering and the advancement of new restorative systems.”
” Delivery of therapeutic particles is a major bottleneck for medication, and we will require a deep bench of alternatives to get these effective new treatments into the ideal cells in the body,” included Zhang. “By gaining from how nature transports proteins, we were able to develop a new platform that can assist resolve this space.”
Zhang is senior author on the study and is likewise the James and Patricia Poitras Professor of Neuroscience at MIT and a detective at the Howard Hughes Medical Institute.
Injection through contraction
Cooperative germs utilize the roughly 100-nanometer-long syringe-like devices to inject proteins into host cells to assist change the biology of their environments and boost their survival. These makers, called extracellular contractile injection systems (eCISs), include a rigid tube inside a sheath that agreements, driving a spike on the end of the tube through the cell membrane. This forces protein cargo inside television to go into the cell.
On the outside of one end of the eCIS are tail fibers that recognize specific receptors on the cell surface and latch on. Previous research study has revealed that eCISs can naturally target pest and mouse cells, but Kreitz thought it may be possible to customize them to deliver proteins to human cells by reengineering the tail fibers to bind to various receptors.
Cancer cells killed by programmed Photorhabdus virulence cassettes, imaged with a scanning electron microscopic lense. Credit: Joseph Kreitz/Broad Institute, McGovern Institute
Using AlphaFold, which forecasts a proteins structure from its amino acid series, the researchers revamped tail fibers of an eCIS produced by Photorhabdus bacteria to bind to human cells. By reengineering another part of the complex, the scientists fooled the syringe into delivering a protein of their picking, sometimes with incredibly high effectiveness.
The team made eCISs that targeted cancer cells revealing the EGF receptor and showed that they killed practically 100 percent of the cells, but did not affect cells without the receptor. Though efficiency depends in part on the receptor the system is created to target, Kreitz says that the findings show the guarantee of the system with thoughtful engineering.
The researchers likewise utilized an eCIS to deliver proteins to the brain in live mice– where it didnt provoke a detectable immune action, suggesting that eCISs could one day be used to safely provide gene therapies to human beings.
Packaging proteins
Kreitz states the eCIS system is flexible, and the group has currently utilized it to deliver a variety of freights including base editor proteins (which can make single-letter changes to DNA), proteins that are harmful to cancer cells, and Cas9, a big DNA-cutting enzyme utilized in many gene editing systems.
Photorhabdus virulence cassettes (green) binding to insect cells (blue) prior to injection of payload proteins. Credit: Joseph Kreitz/Broad Institute, McGovern Institute
In the future, Kreitz states researchers might craft other parts of the eCIS system to tune other properties, or to provide other cargos such as DNA or RNA. He likewise wishes to better understand the function of these systems in nature.
” We and others have shown that this type of system is extremely diverse throughout the biosphere, but they are not effectively identified,” Kreitz stated. “And we think this type of system plays actually crucial roles in biology that are yet to be checked out.”
Reference: “Programmable protein shipment with a bacterial contractile injection system” by Joseph Kreitz, Mirco J. Friedrich, Akash Guru, Blake Lash, Makoto Saito, Rhiannon K. Macrae and Feng Zhang, 29 March 2023, Nature.DOI: 10.1038/ s41586-023-05870-7.
This work was supported in part by the National Institutes of Health, Howard Hughes Medical Institute, Poitras Center for Psychiatric Disorders Research at MIT, Hock E. Tan and K. Lisa Yang Center for Autism Research at MIT, K. Lisa Yang and Hock E. Tan Molecular Therapeutics Center at MIT, K. Lisa Yang Brain-Body Center at MIT, Broad Institute Programmable Therapeutics Gift Donors, Pershing Square Foundation, W. Ackman, N. Oxman, J. and P. Poitras, BT Charitable Foundation, C. and L. Asness, the Phillips family, D. Cheng, and R. Metcalfe.

Cleansed Photorhabdus virulence cassettes (PVCs), imaged using TEM. Credit: Joseph Kreitz, Broad Institute of MIT and Harvard, McGovern Institute for Brain Research at MIT
Bacterial Injection System Delivers Proteins in Mice and Human Cells
With additional development, the programmable system could be utilized in a variety of applications consisting of gene therapy and cancer therapy.
Researchers at the Broad Institute of MIT and Harvard and the McGovern Institute for Brain Research at MIT have actually harnessed a natural bacterial system to establish a new protein shipment approach that operates in human cells and animals. The innovation, explained recently in the journal Nature, can be set to deliver a range of proteins, consisting of ones for gene modifying, to different cell types. The system might potentially be a effective and safe method to deliver gene treatments and cancer therapies.
Led by Broad core institute member and McGovern Institute private investigator Feng Zhang, the group benefited from a tiny syringe-like injection structure, produced by a bacterium, that naturally binds to insect cells and injects a protein payload into them. The scientists utilized the synthetic intelligence tool AlphaFold to craft these syringe structures to deliver a variety of helpful proteins to both human cells and cells in live mice.

Scientists at the Broad Institute of MIT and Harvard and the McGovern Institute for Brain Research at MIT have utilized a natural bacterial system to develop a new protein shipment method that works in human cells and animals. The innovation, explained recently in the journal Nature, can be configured to deliver a range of proteins, consisting of ones for gene editing, to various cell types. Cooperative bacteria utilize the roughly 100-nanometer-long syringe-like machines to inject proteins into host cells to help adjust the biology of their environments and boost their survival. These machines, called extracellular contractile injection systems (eCISs), consist of a rigid tube inside a sheath that agreements, driving a spike on the end of the tube through the cell membrane. This forces protein cargo inside the tube to go into the cell.