A novel trans conformation of ligand-free calmodulinKumar, V., Chichili, V.P.R., Tang, X., Sivaraman, J.
(2013) PLoS One 8: e54834-e54834
- PubMed: 23382982
- DOI: https://doi.org/10.1371/journal.pone.0054834
- Primary Citation of Related Structures:
- PubMed Abstract:
Calmodulin (CaM) is a highly conserved eukaryotic protein that binds specifically to more than 100 target proteins in response to calcium (Ca(2+)) signal. CaM adopts a considerable degree of structural plasticity to accomplish this physiological role; however, the nature and extent of this plasticity remain to be fully understood. Here, we report the crystal structure of a novel trans conformation of ligand-free CaM where the relative disposition of two lobes of CaM is different, a conformation to-date not reported. While no major structural changes were observed in the independent N- and C-lobes as compared with previously reported structures of Ca(2+)/CaM, the central helix was tilted by ~90° at Arg75. This is the first crystal structure of CaM to show a drastic conformational change in the central helix, and reveals one of several possible conformations of CaM to engage with its binding partner.
Department of Biological Sciences, National University of Singapore, Republic of Singapore, Republic of Singapore.