Structure, dynamics and phosphorylation regulation of Ubiquitin system

  • Posted on: 28 July 2020
  • By: liuk

Noncovalent Dimerization of Ubiquitin

Using the PRE NMR, we found a weak non-covalent interaction between ubiquitin monomers (Kd≈5 mM), and analyzed the dimer ensemble structure. Besides, a new regulatory mechanism for the interaction between ubiquitin and ubiquitin-binding proteins has been proposed.
Reference: Angew Chem Int Ed, 2012, 51, 469-472.

Dynamic Structure and Function Regulation of K63-diUb

By integrating PRE, SAXS and other methods, we have analyzed the ensemble structure of K63-diUb, and revealed the molecular mechanism by which the ubiquitin chain binds to different target proteins through different conformations, thereby performing different biological functions.
Reference: eLife, 2015, 4:e05767.

Regulation of ubiquitin phosphorylation on its structure and function

Through the integration of NMR, smFRET, MD simulation and other methods, it is revealed that the ubiquitin monomer will exhibit four mutually transformable conformations after Ser65 phosphorylation. It is proposed that pH can affect the structure of the protein and regulate the mutual transformation of multiple conformations by adjusting the protonation level of the phosphate group. In addition, Ubiquitin can also be double-phosphorylated by PINK1 and enhance the sensitivity of conformational transformation to pH changes.
Reference: Proc Natl Acad Sci, USA, 2017, 114:6770-6775. 
                  Protein & Cell, 2019, 10:908-913.

Integration of smFRET and NMR to study the dynamic structure and function of K48-linked ubiquitin chain

K48 linked ubiquitin chains can mediate the degradation of substrate protein by Proteasome. This study uses NMR as the main method to analyze the solution structure of K48-diUb:Rpn13NTD, In addition, using smFRET we proved that Rpn13 specifically binds to the closed state of the K48 linked ubiquitin chains through conformational selection. This work provides the structural baisis for Rpn13 linkage selectivity, which opens a new window for modulating proteasomal function.
Reference: Cell Discov, 2019, 5:9.