A Novel Trans Conformation of Ligand-Free Calmodulin
Kumar, V. Chichili, V.P.R. Tang, X. Sivaraman, J.
Kumar, V.
Chichili, V.P.R.
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Abstract
Calmodulin (CaM) is a highly conserved eukaryotic protein that binds specifically to more than 100 target proteins in response to calcium (Ca2+) 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 Ca2+/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. © 2013 Kumar et al.
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PLoS ONE
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Date
2013-01-29
DOI
10.1371/journal.pone.0054834
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Article