Structural transformation of the tandem ubiquitin-interacting motifs in ataxin-3 and their cooperative interactions with ubiquitin chains.
The ubiquitin-interacting motif (UIM) is a short peptide with dual function of binding ubiquitin (Ub) and promoting ubiquitination. We elucidated the structures and dynamics of the tandem UIMs of ataxin-3 (AT3-UIM12) both in free and Ub-bound forms. The solution structure of free AT3-UIM12 consists of two α-helices and a flexible linker, whereas that of the Ub-bound form is much more compact with hydrophobic contacts between the two helices. NMR dynamics indicates that the flexible linker becomes rigid when AT3-UIM12 binds with Ub. Isothermal titration calorimetry and NMR titration demonstrate that AT3-UIM12 binds diUb with two distinct affinities, and the linker plays a critical role in association of the two helices in diUb binding. These results provide an implication that the tandem UIM12 interacts with Ub or diUb in a cooperative manner through an allosteric effect and dynamics change of the linker region, which might be related to its recognitions with various Ub chains and ubiquitinated substrates.
Song
Ai-Xin
AX
State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.
Zhou
Chen-Jie
CJ
Peng
Yu
Y
Gao
Xue-Chao
XC
Zhou
Zi-Ren
ZR
Fu
Qing-Shan
QS
Hong
Jing
J
Lin
Dong-Hai
DH
Hu
Hong-Yu
HY
D000067699:Ataxin-3; D008958:Models, Molecular; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism*
D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D025801:Ubiquitin; C092341:ATXN3 protein, human; D000067699:Ataxin-3