It's a "puzzle" race among scientists. For science, RNA polymerase is equivalent to the CPU (central processing unit) of the cell, and understanding its structure and working mechanism can understand the core essence of the lowest layer of life.
The zhang yu research team of the Center for Excellence in Molecular Plant Science of the Chinese Academy of Sciences, the research team of Wang Jiawei and the team of Feng Yu of Zhejiang University cooperated to successfully analyze the structure of the fourth RNA polymerase of eukaryotes, which is a major breakthrough in the frontier field of molecular biology and plant science. On December 24, 2021, the research results were published in the international authoritative journal Science.
[American scientist won the 2006 Nobel Prize in Chemistry for resolving the structure of RNA polymerase II]
Plants have 5 RNA polymerases, from 2000 to 2015, American and German scientists have successively resolved the three-dimensional structure of the first three RNA polymerases, of which the American scientist Roger Kornberg also won the 2006 Nobel Prize in Chemistry for analyzing the structure of RNA polymerase II. However, because the fourth RNA polymerase evolved independently into a new branch hundreds of millions of years ago, its physiological function is significantly different from the first three, and its three-dimensional structure and working mechanism have been difficult to answer.
A fourth RNA polymerase plays a central role in inhibiting genomic transposons. Transposons were first discovered by American geneticist Barbara McClintock. In the genomes of plants and animals, there are a large number of transposon regions, such as rice 35%, corn as high as 85%, and humans as close as 50%. Transposons are able to "copy and paste" their own DNA in the host genome for the purpose of self-"reproduction", and the activity of transposons poses a serious threat to the stability of the genome. McClintock's discovery eventually earned her the 1983 Nobel Prize in Physiology and Medicine.
[Isolation of the fourth RNA polymerase sample of purified plants is the biggest bottleneck]
"The biggest difficulty in analyzing the three-dimensional structure of the fourth RNA polymerase is to obtain protein samples, which is also a technical bottleneck that has plagued scientists at home and abroad for 20 years." Zhang Yu told the Jiefang Daily Shangguan News reporter that there are more than 20,000 proteins in the plant, and the content of the fourth RNA polymerase is extremely low, and it has been difficult to isolate and purify before.
Researcher Zhang Yu has been pondering this scientific problem since he was a postdoc, and the turning point occurred in a conversation with Wang Jiawei. The collision of different professional directions led the two young men to decide to innovate the experimental method of modifying plant suspension cells to obtain a protein sample of the fourth RNA polymerase.
Zhang Yu (left) discusses with Wang Jiawei
Under the unremitting efforts of Huang Kun, the first author of the research paper and a doctoral student, the collaborative team purified and isolated a high-quality sample of the fourth RNA polymerase protein complex and resolved its three-dimensional structure.
Zhang Yu introduced that this complex is like two workshops, its interior is connected by a "tunnel", and the products of one workshop (single-stranded RNA) are transmitted to another workshop through the "tunnel" to continue to complete the synthesis of the second chain. Together, they produce double-stranded RNA molecules that can help plant cells accurately label transposon DNA with methylation "branding."
"Life is so amazing, it works a bit like a two-sided printer, printing one side first and then the other." Wang Jiawei still vividly remembers the excitement and excitement of one weekend when he and Zhang Yu first saw the three-dimensional structure of the complex, "Being able to achieve original results that may be written into textbooks is the greatest pleasure of doing scientific research." ”
"Compared with the strong scientific research team abroad, these two young research teams are not many people, and the number of participants is only single digits, but their work is not simple, not only solves a major scientific problem, but also has important reference value for people to understand the evolution of plants and animals, as well as the nature of life." Han Bin, director of the Center for Excellence in Molecular Plant Science of the Chinese Academy of Sciences and academician of the Chinese Academy of Sciences, said.