KANAZAWA, Japan, December 8, 2021 / PRNewswire / – In a recent study published in the Journal of Extracellular Vesicles, researchers at the University of Kanazawa have visualized structural changes on the surface of SARS-CoV-2 that allow it to enter human cells.
The biology of SARS-CoV-2, the virus that caused the COVID-19 pandemic, remains partially elusive. Understanding viral mechanisms is a key factor in developing effective treatment strategies for the epidemic. Now Keesiang Lim and Richard wong from Kanazawa University and colleagues showed how the virus is equipped to enter human cells in real time.
SARS-CoV-2 is enveloped in spike proteins, which form a crown-like layer on its surface. The immune system detects these spike proteins and prepares to neutralize the virus. The spike proteins also play a role in mediating the entry of SARS-CoV-2 into cells. To date, scientists have been able to take high-resolution albeit stationary images of advanced proteins. Above all, Richard Wong’s The team and the University of Kanazawa used an advanced form of microscopy to capture dynamic changes in spike proteins as they bind to cells.
Spike proteins consist of two main components: a globular head (which has a host recognition domain) attached to a rod (which is able to fuse with cells and facilitate entry). The researchers used high-speed atomic force microscopy (HS-AFM) to understand this structure more in depth using only single advanced protein molecules.
“We have previously shown that real-time observation of the structural dynamics of influenza A hemagglutinin upon viral entry,” says lead author of the study, Dr. Keesiang Lim.
In the recently published study, they found that the rod exhibited a very flexible nature with an ability to expand or retract as the head could change conformation, causing the host’s recognition domain to disappear. Spike proteins usually attach to cells that have a molecule called ACE2 on their surface. Thus, the interactions of the spike proteins with ACE2 were then visualized by HS-AFM. The spike proteins were found to dock at ACE2 with the host recognition domain exposed. In addition, their elastic nature allowed for a much smoother interaction.
Small extracellular vesicles (sEV) are sacs released by cells that are made up of the same chemical constituents as the cell membrane. The dynamics of the peak proteins on the sEVs were then studied. Since the spike protein rod facilitates binding and fusion with membranes, only interactions of the rod with sEVs were analyzed first. Indeed, a rupture of the sEV membranes was observed, indicating that the rod could easily fuse with the cell membranes. However, when the dynamics of the entire spike protein were assessed, stable binding was only observed with sEVs released from cells containing ACE2. ACE2 was therefore a key factor in mediating viral entry.
The HS-AFM has proven to be a very useful tool to understand in detail the entry mechanisms of SARS-CoV-2. “Overall, our study provides a suitable platform for real-time visualization of various entry inhibitors, neutralizing antibodies, and sEV-based decoy to block viral entry,” explains Dr. Richard wong, lead author of the study. “Blocking connections between spike proteins and ACE2 or inhibiting membrane disruption caused by the spike protein stem could be potential strategies preventing SARS-CoV-2 from hijacking the body.”
Background
ACE2: Angiotensin converting enzyme 2, or ACE2, is a protein found on the membrane of cells located in the upper respiratory tract, intestines, kidneys, heart, and other organs. The physiological role of ACE2 is to metabolize hormones and stimulate their function.
ACE2 is also a reception point for several coronaviruses. The virus-ACE2 complex is engulfed in the cell, which facilitates entry of the pathogen. In addition, SARS-CoV-2 is known to bind to ACE2 more effectively than SARS-CoV-1 which was responsible for the SARS epidemic. Understanding the dynamics of SARS-CoV-2 and ACE2 interactions is therefore essential to develop strategies aimed at preventing viral entry.
Small Extracellular Vesicles (sEV): The cells in our body release small vesicles that allow them to transport biomolecules, communicate with other cells, and release signals when pathogens are detected. The sEVs are a subset of these vesicles with a very small particle size. These vesicles are created when a cell’s membrane pinches into smaller, bag-like structures. The membranes of evs therefore closely resemble those of living cells.
Since sEVs are released in various infections and cancers, they are also being studied as therapeutic targets. For example, sEVs containing ACE2 could be used as bait to trap SARS-CoV-2 and then neutralize the virus.
Reference
Keesiang Lim, Goro Nishide, Takeshi Yoshida, Takahiro Watanabe-Nakayama, Akiko Kobayashi, Masaharu Hazawa, Rikinari Hanayama, Toshio Ando, Richard W. Wong. Millisecond dynamics of the SARS-CoV-2 peak and its interaction with the ACE2 receptor and small extracellular vesicles. Journal of Extracellular Vesicles, 2021.
DOI: 10.1002 / jev2.12170
https://doi.org/10.1002/jev2.12170
Associated figures
https://nanolsi.kanazawa-u.ac.jp/wp-content/uploads/2021/12/fig-1.jpg
Figure 1. The molecular dynamics of the spike protein (Spike / S) of the coronavirus SARS-CoV-2 has been successfully observed directly for the first time in the world using HS-AFM.
https://nanolsi.kanazawa-u.ac.jp/wp-content/uploads/2021/12/fig-2.jpg
Figure 2: Overview: Direct visualization of the interaction of coronavirus spike proteins with angiotensin converting enzyme 2 (ACE2) binding in real time using HS-AFM.
Contact
Hiroé Yoneda
Vice Director of Public Affairs
WPI Nano Life Science Institute (WPI-NanoLSI)
Kanazawa University
Kakuma-machi, Kanazawa 920-1192, Japan
E-mail: [email protected]
Phone. : +81 (76) 234-4550
About the Nano Life Science Institute (WPI-NanoLSI)
Nano Life Science Institute (NanoLSI), the University of Kanazawa is a research center established in 2017 as part of the Global Initiative of the International Research Center of the Ministry of Education, Culture, Sports, Science and Technology. The objective of this initiative is to form world-class research centers. NanoLSI combines the most advanced knowledge in biological scanning probe microscopy to establish “nano-endoscopic techniques” allowing to directly image, analyze and manipulate biomolecules to better understand the mechanisms governing the phenomena of life such as diseases.
About Kanazawa University
http://www.kanazawa-u.ac.jp/e/
As the leading comprehensive university on the sea of Japan coast, Kanazawa University has greatly contributed to higher education and university research in Japan since its founding in 1949. The university has three colleges and 17 schools offering courses in fields such as medicine, computer engineering and the humanities.
The University is located on the sea coast of Japan in Kanazawa – a city rich in history and culture. The city of Kanazawa has had a highly respected intellectual profile since the days of the fiefdom (1598-1867). Kanazawa University is divided into two main campuses: Kakuma and Takaramachi for its approximately 10,200 students including 600 from overseas.
SOURCE Kanazawa University
