Structural and functional characterization of a calcium-activated cation channel from Tsukamurella paurometabola.
The selectivity filter is an essential functional element of K+channels that is highly conserved both in terms of its primary sequence and its three-dimensional structure. Here, we investigate the properties of an ion channel from the Gram-positive bacterium Tsukamurella paurometabola with a selectivity filter formed by an uncommon proline-rich sequence. Electrophysiological recordings show that it is a non-selective cation channel and that its activity depends on Ca2+concentration. In the crystal structure, the selectivity filter adopts a novel conformation with Ca2+ions bound within the filter near the pore helix where they are coordinated by backbone oxygen atoms, a recurrent motif found in multiple proteins. The binding of Ca2+ion in the selectivity filter controls the widening of the pore as shown in crystal structures and in molecular dynamics simulations. The structural, functional and computational data provide a characterization of this calcium-gated cationic channel.
Division of Biological Sciences, Department of Biochemistry and Molecular Biology, The University of Chicago 929 East 57th Street Chicago, Illinois 60637, USA.
Balasundaresan
B
Dhakshnamoorthy
Division of Biological Sciences, Department of Biochemistry and Molecular Biology, The University of Chicago 929 East 57th Street Chicago, Illinois 60637, USA.|Department of Biophysics, Faculty of Science, Cairo University, Giza, 12613, Egypt.
Ahmed
A
Rohaim
Division of Biological Sciences, Department of Biochemistry and Molecular Biology, The University of Chicago 929 East 57th Street Chicago, Illinois 60637, USA.
Huan
H
Rui
Division of Biological Sciences, Department of Biochemistry and Molecular Biology, The University of Chicago 929 East 57th Street Chicago, Illinois 60637, USA.
Lydia
L
Blachowicz
Division of Biological Sciences, Department of Biochemistry and Molecular Biology, The University of Chicago 929 East 57th Street Chicago, Illinois 60637, USA.
Benoît
B
Roux
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