Coiled coil has served as an excellent model system for studying protein folding and developing protein-based biomaterials. Most designed coiled coils function as oligomers, namely intermolecular coiled coils. However, less is known about structural and biochemical behavior of intramolecular coiled coils where coiled coil domains are covalently linked in one polypeptide. Here we prepare a protein which harbors three coiled coil domains with two short linkers, termed intramolecular tandem coiled coil (ITCC) and characterize its structural and biochemical behavior in solution. ITCC consists of three coiled coil domains whose sequences are derived from Coil-Ser and its domain swapped dimer. Modifications include positioning E (Glu) residue at "e" and K (Lys) at "g" positions throughout heptad repeats to enhance ionic interaction among its constituent coiled coil domains. Molecular modeling of ITCC suggests a compact triple helical bundle structure with the second and the third coiled coil domains forming a canonical coiled coil. ITCC exists as a mixture of monomeric and dimeric species in solution. Small-angle X-ray scattering reveals ellipsoidal molecular envelopes for both dimeric and monomeric ITCC in solution. The theoretically modeled structures of ITCC dock well into the envelopes of both species. Higher ionic strength shifts the equilibrium into monomer with apparently more compact structure while secondary structure remains unchanged. Taken together, our results suggest that our designed ITCC is predominantly monomeric structure through the enhanced ionic interactions, and its conformation is affected by the concentration of ionic species in the buffer.
|Number of pages||8|
|Journal||Biochemical and Biophysical Research Communications|
|Publication status||Published - 2014 Dec 12|
Bibliographical noteFunding Information:
We thank the staff at the beamlines 4C of Pohang Accelerator Laboratory and F1 of CHESS for technical assistance in collecting SAXS data, and Dr. Kyeong Kyu Kim for access to a CD machine. This work was supported by the National Junior Fellowship ( NRF-2011-0001779 ) to D. Shin., Undergraduate Research Program ( 2009-04-405 , 2010-D-056 ) through the Korea Foundation for the Advancement of Science and Creativity (KOFAC) to D. Shin and G. Kim., the Rural Development Agency through the Woo Jang Chun Program ( PJ009106 ), and the Pioneer Research Center Program ( 2012-0009597 ) through the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT and Future Planning to S. Lee.
© 2014 Elsevier Inc. All rights reserved.
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology