BY Ai Dandi, SUSTC News Agency

On December 25, 2015, Director-General Xu Ruiming of Frontier Sciences and Education, Chinese Academy of Sciences was invited to the 54th session of SUSTC Lectures to give a lecture on “molecular mechanism in epigenetics”. The lecture was chaired by Professor Xiao Guozhi, Dean of SUSTC Department of Biology.

In his lecture, Professor Xu Ruiming explained in detail the concept of epigenetic, the theory of yeast genetics and the major research orientation of structural biology, enlightening the audiences greatly.

Epigenetics means no change happens to DNA sequence with gene expression experiencing inheritable changes. Such changes are those of other heritable substances in cells except the genetic information. Besides, such changes can be stably passed on in the process of development and cell proliferation. Professor Xu Ruiming gave the definition of epigenetics before explaining decisive factors of epigenetics, of which the most important ones are DNA methylation and the major protein modification.

Specific mechanism of yeast epigenetics

In the same yeast from one generation to the next, there is a hermaphroditegene that is in explicit non-expression. But what mechanism has caused the non-expression? This section of gene has 2 sequences, e.g., Esilencer on the one end and Isilencer on the other. And a fixed-point sequence is used to recruit the other few proteins. After the recruitment, all the proteins are in these two DNA sequences modified by silencer. Those between the 2 DNA sequences are non-expression.

In addition to the specific mechanism of yeast inheritance, Professor Xu Ruiming also introduced major orientation of 2 types of structural biology, e.g., the new-type testing and NMR.

SIR2 and SIR3

By using vivid metaphor, Professor Xu Ruiming also explained the structure, function and differentiation of sir2, thus deepening the students’ understanding of yeast. “We also have made some studies about sir3, which is a large protein with nearly 1,000 amino acid. Later on, we find that if we decode the N end, it can fulfill the function of the entire protein chain. Though the C end is very important, if we over-express the N end, it would become the original total length.”

In the Q&A session, Professor Xu introduced about more knowledge of essential biology while exploring the specific definitions and roles of sir2 and sir4 in the yeast.