PMID: 23382982

Authors:

Kumar V, Chichili VP, Tang X, Sivaraman J

Title:

A novel trans conformation of ligand-free calmodulin.

Journal:

PLoS One. 2013;8(1):e54834. doi: 10.1371/journal.pone.0054834. Epub 2013 Jan 29.

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 approximately 90 degrees 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.