Xinhua News Agency, Beijing, April 21 (Reporters Quan Xiaoshu, Li Mi, Gao Bei) cannot live without protein. How to use and develop advanced technical means to observe these nano-scale small worlds has always been a frontier area of focus in the scientific community.
In 2011, China began to prepare for the establishment of the National Protein Science Research Facility. As an important base of the facility, Tsinghua University has built the world's leading cryo-electron microscope (hereinafter referred to as "cryo-electron microscope") platform in the past ten years. With this advantage, Chinese scientists have made many remarkable achievements in the field of protein structure research.
For example, Shi Yigong, a famous structural biologist, led a team to conduct a series of studies on the spliceosome responsible for inheritance in the nucleus, and the results have been published in top international journals; Tsinghua University professor Sui Senfang led a team to develop a protein complex that captures light energy in plants. important structure analysis.
"There are hundreds of thousands of different proteins, nucleic acids and their complexes in the human body, they are like tiny molecular machines. If you can figure out what parts they are made of and how these parts are assembled, It is of great significance to understand how the molecular machine itself works and how to repair the malfunctioning machine." said Wang Hongwei, the main builder of Tsinghua's cryo-EM platform and dean of the School of Life Sciences, Tsinghua University.
In the first decade of this century, cryo-electron microscopy was still a niche technology that was not favored. It was during this period that Tsinghua University decided to start building a cryo-EM platform, which won a valuable opportunity for the development of life sciences in China.
"It now seems that this is a very important decision, and it has played a very important role in China's leading position in the world in the field of cryo-electron microscopy in the past decade." Wang Hongwei said.
The researchers of the cryo-electron microscope platform of the Protein Research Technology Center of Tsinghua University process the cryo-electron microscope images by computer. Photo by Xinhua News Agency reporter Wu Meng
The mystery of freezing life
In the 1930s, the world's first electron microscope came out, and scientists have been able to observe the internal structure of cells since then. However, when looking at biological samples in their natural state, such as protein macromolecules, electron microscopy is powerless.
Wang Hongwei explained that biological samples contain water, but the interior of the electron microscope is generally in a high vacuum state. When biological samples are placed in it, the water will evaporate quickly. "It's like when we observe mummies, what we see is not the natural state of the human body."
In the 1970s and 1980s, scientists gradually developed cryo-electron microscopy technology, but there is still a big gap between mature applications. Structural biology more use X-ray crystallography, but the problem is that many complex macromolecular substances are difficult to obtain crystals.
Over the past ten years, cryo-electron microscopy technology has continued to improve, like casting a beam of light into the thick fog of life. In 2017, three scientists who developed cryo-EM technology were awarded the Nobel Prize in Chemistry.
"We drop the biomacromolecule solution on a metal carrier grid with a diameter of only 3 to 4 mm, forming a very thin water film, and then freeze it to the temperature of liquid nitrogen (below -196°C) in milliseconds. Because the speed is very fast, the water in the biological samples cannot be crystallized, and there is no time to evaporate, but a thin layer of ice is formed. We can then keep such samples at a low temperature and place them under an electron microscope to observe their internal structure. "Wang Hongwei said. Since the outbreak of
new crown virus, scientists have carried out a series of reconstruction and research on new crown virus with cryo-electron microscopy technology.For example, the team of Wang Xinquan and Zhang Linqi of Tsinghua University used cryo-electron microscopy to analyze the mutations of some key amino acid sites in the receptor binding region of the spike protein on the surface of the new coronavirus.
"Based on these site mutations, researchers can evaluate, modify or design drugs and vaccines to make them more specific." Wang Hongwei said that serving modern biopharmaceuticals is an important goal of cryo-EM technology development.
Wang Hongwei, Dean of the School of Life Sciences of Tsinghua University, was interviewed by a reporter from Xinhua News Agency. Xinhua News Agency reporter Wu Meng photographed
A once-in-a-lifetime opportunity
recalling the experience of returning to China to build a cryo-electron microscope platform in the past ten years, Wang Hongwei said with emotion: his income has always exceeded expectations.
went to the United States as a postdoctoral fellow in 2001, and became an assistant professor of at Yale University in 2009 and set up an independent laboratory. Wang Hongwei could have realized his academic dream earlier along the established track. At the end of 2009, Wang Hongwei returned to China to visit relatives. At his alma mater, Tsinghua University, he met Professor Shi Yigong, then Deputy Dean of the Institute of Life Sciences and Medicine of Tsinghua University, and his mentor, Academician Sui Senfang. The two invited him to return to China to build a world-class cryo-electron microscopy center. .
In 2009, Asia's first cryo-electron microscope was installed in Tsinghua University, but the direction of this technology is still unclear. Western counterparts even questioned whether anyone will use cryo-electron microscopy equipment in the future Opportunity." recalled the scientist who has been engaged in cryo-electron microscopy research since he entered Tsinghua as a doctoral student in 1996.
In 2011, Wang Hongwei resigned from his job at Yale University and returned to Tsinghua University, from personnel to equipment, from scratch.
In 2014, the cryo-EM equipment at Tsinghua base was basically in place, and China became a leader in this field.What makes Wang Hongwei even more happy is that, precisely during this period, breakthroughs in cryo-EM technology from hardware to software have greatly improved the efficiency and accuracy of this technology.
Driven by the wave of technological innovation, Professor Lei Jianlin, Director of Tsinghua Cryo-EM Platform, developed a set of automatic data collection software. "Before, researchers had to sit in front of the microscope to manually take pictures one by one, and each one had to manually adjust the relevant parameters. To collect a set of data for a project, hundreds to thousands of pictures need to be taken. It will take several days before I sit down." Wang Hongwei said.
"Now, as long as it takes two or three hours to select samples and set parameters, everything can be done automatically by the computer, which not only improves the efficiency, but also makes the microscope more stable," he said.
The first cryo-EM facility in Tsinghua University. Photo by Xinhua News Agency reporter Quan Xiaoshu
Take time to sharpen your own knife
At present, Tsinghua's cryo-EM platform has more than ten devices, including four high-end devices of 300 kV, all of which operate at full capacity 24 hours a day and can complete the Data collection for two or three hundred projects.
"Even so, it is not enough to meet the demand. The users we face have expanded from the original field of structural biology to the field of cell biology and even neurobiology. In the future, clinicians may use our equipment. Therefore, the demand will increase. Come bigger." Wang Hongwei said.
Tsinghua cryo-EM platform is not only for domestic users, but also open to the world from the beginning of construction. It has served scientific research teams from around the world including the US, UK, Japan and Singapore over the past decade.
"The Tsinghua base organizes one or two technical training courses or academic exchanges for the world almost every year. The cryo-EM center and better use of cryo-EM technology have laid a good foundation," said Wang Hongwei.
However, Wang Hongwei is very clear that in order to maintain the advantages and vitality of innovation, it is not enough to add a few devices. There is also a major shortcoming that needs to be overcome – China currently does not have the ability to produce its own cryo-EM equipment. The cryo-EM equipment used by all scientific research institutes in China, ranging from as small as a screw to the most complex electron gun components, all come from foreign manufacturers.
"This is also a question we have been thinking about." Wang Hongwei pointed out that his team has been researching and developing original cryo-EM techniques and methods, including innovative instruments and equipment.
China's "14th Five-Year Plan" and the outline of its long-term goals for 2035 require that science and technology be self-reliant and self-reliant as a strategic support for national development.
Wang Hongwei believes that the development of cryo-EM tools and methods with independent intellectual property rights should be the focus of the next step. "In the past, we bought knives from others, and the results of chopping wood were obvious. Now, we have to spend time sharpening our own knives to chop more and better wood."
