China University of Science and Technology Dynasty Research Group has made progress in the study of the mechanism of Ephexin family protein auto-inhibition and activation

Ephrin-Eph signaling pathway regulates cytoskeleton dynamic changes by regulating the activity of downstream Rho GTPase , and plays a key role in neural development and signal transduction, cell polarity, cell migration, metabolic balance and other processes .

Eph receptors are the largest branch of the tyrosine protein kinase receptor family, which can recruit multiple Rho GTPase regulatory protein complexes ( RhoGEF and RhoGAP ) to function .

Recently, Professor Wang Chao's research group from the Department of Life Science and Medicine of the University of Science and Technology of China and Professor Zhu Jinwei 's research group from the Bio-X Research Institute of Shanghai Jiao Tong University jointly published a research paper titled Double inhibition and activation mechanisms of Ephexin family RhoGEFs on PNAS online , revealing for the first time Molecular mechanism of dual autoinhibition and activation of Ephexin family RhoGEF .

This work found that the auto-inhibition of Ephexin4 RhoGEF consists of two parts: 1 ) Its carboxyl-terminal SH3-HC tandem domain can interact with the GEF enzyme activity center - DH-PH domain, thereby hindering the entry of RhoG and inhibiting the catalytic reaction; 2 ) a conserved polypeptide sequence ( IH polypeptide sequence) at the amino terminus can also bind to the DH domain and inhibit the enzymatic activity of Ephexin4 .

In this work , the three-dimensional structural information of the carboxyl-terminal auto-inhibition and double auto-inhibition of Ephexin4 were studied by means of structural biology, and the structural basis and molecular mechanism of Ephexin4 auto-inhibition were elucidated in detail (Figure 1 )
.

Interestingly, structural analysis revealed that key residues at the auto-inhibitory interface (such as R706 ) were mutated in tumors ( R706L ), and this mutation would break the auto-inhibitory conformation, thereby activating the enzymatic activity of Ephexin4 .
Biochemical experiments also confirmed this structural analysis (Figure 1 ) .

 

Figure 1.

N -terminal autoinhibited conformation of Ephexin4

 

This work further explores the possible mechanism of Ephexin4 auto-inhibitory conformational activation
.

The authors found that, DLG I or Tip1 protein PDZ domains can bind Ephexin4 carboxy terminal PDZ binding sequence ( PDZ-Binding Motif , PBM ); this interaction can effectively activate Ephexin4 autoinhibitory carboxy terminus

 

Figure 2.

Schematic diagram of the molecular mechanism of dual autoinhibition and activation of Ephexin family RhoGEF

 

In conclusion , this work clarifies the molecular mechanism of dual auto-inhibition and activation of Ephexin family proteins by comprehensively applying structural biology, biochemistry and cell biology methods, and provides a reliable basis for the pathogenesis of related neurological diseases and tumors.

Structural elucidation and provide a basis for the development of related drugs .

 

Professor Wang Chao from University of Science and Technology of China and Professor Zhu Jinwei from Shanghai Jiaotong University are the co-corresponding authors of the paper.

Zhang Meng, a doctoral student at University of Science and Technology of China, and Lin Lin, an assistant researcher at Shanghai Jiaotong University, are the co-first authors of the paper

 

Paper link:https://doi.

org/10.
1073/pnas.
2024465118

 

( Key Laboratory of Membraneless Organelles and Cell Dynamics, Ministry of Education, Hefei National Research Center for Microscale Matter Science, Department of Life Science and Medicine, and Research Department)