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.
State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.
Ai-Xin
AX
Song
Chen-Jie
CJ
Zhou
Yu
Y
Peng
Xue-Chao
XC
Gao
Zi-Ren
ZR
Zhou
Qing-Shan
QS
Fu
Jing
J
Hong
Dong-Hai
DH
Lin
Hong-Yu
HY
Hu
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