Biophysical characterization of the structural change of Nopp140, an intrinsically disordered protein, in the interaction with CK2α

Jung Hyun Na, Won Kyu Lee, Yuyoung Kim, Cherlhyun Jeong, Seung Soo Song, Sun Shin Cha, Kyou Hoon Han, Yeon Kyun Shin, Yeon Gyu Yu

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Nucleolar phosphoprotein 140 (Nopp140) is a nucleolar protein, more than 80% of which is disordered. Previous studies have shown that the C-terminal region of Nopp140 (residues 568–596) interacts with protein kinase CK2α, and inhibits the catalytic activity of CK2. Although the region of Nopp140 responsible for the interaction with CK2α was identified, the structural features and the effect of this interaction on the structure of Nopp140 have not been defined due to the difficulty of structural characterization of disordered protein. In this study, the disordered feature of Nopp140 and the effect of CK2α on the structure of Nopp140 were examined using single-molecule fluorescence resonance energy transfer (smFRET) and electron paramagnetic resonance (EPR). The interaction with CK2α was increased conformational rigidity of the CK2α-interacting region of Nopp140 (Nopp140C), suggesting that the disordered and flexible conformation of Nopp140C became more rigid conformation as it binds to CK2α. In addition, site specific spin labeling and EPR analysis confirmed that the residues 574–589 of Nopp140 are critical for binding to CK2α. Similar technical approaches can be applied to analyze the conformational changes in other IDPs during their interactions with binding partners.

Original languageEnglish
Pages (from-to)181-187
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number2
StatePublished - 19 Aug 2016

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea ( NRF-2010-0021725 ), the Basic Science Research Programs through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science, and Technology ( 2013-R1A1A2-062683 and 2015R1A2A1A15056039 ), the KIST institutional Programs ( 2E25520 ), and Korea-Hungary Joint Lab Program from National Research Council of Science and Technology ( NCT2251422 ).

Publisher Copyright:
© 2016 Elsevier Inc.


  • Casein kinase 2
  • Electron para-magnetic resonance
  • Intrinsically disordered protein
  • Nopp140
  • Single-molecule FRET
  • Structural diversity


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