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Title: Structural basis for preferential Ca2+-displacement by a paramagnetic ion (Ce3+) in non-myristoylated neuronal calcium sensor-1
Authors: Chandra, Kousik
Susmitha, A L
Sharma, Y
Chary, K V R
Keywords: Bioinorganic chemistry;Sensors;Neuronal calcium sensor;Calcium displacement;Cerium
Issue Date: Mar-2011
Publisher: NISCAIR-CSIR, India
Abstract: We have investigated the Ca2+-displacement by a trivalent lanthanide ion (Ce3+) in a Ca2+-sensor protein called neuronal calcium sensor-1 in its non-myristoylated form by NMR. We observe that all the Ca2+ bound to the three active Ca2+-binding loops are displaced by Ce3+. Microscopically, NMR paramagnetic titration data on [Ca2+]-non-myr-NCS-1 shows that the Ce3+ displaces Ca2+ first from both sites, EF2 and EF3, almost in parallel, followed by the displacement from EF4. Between EF2 and EF3, the NMR data conclusively shows that the Ca2+-displacement is more prominent in EF2 as compared to that in EF3. These findings have been attributed to: (i) the presence of a higher number of negatively charged residues in EF2 compared to EF3 and EF4, and, (ii) the presence of a Lys instead of a highly conserved Phe at –4 position in the first Ca2+-binding loop, which results in a relatively more open conformation of the N-terminal domain compared to the C-terminal counterpart.
Page(s): 539-547
ISSN: 0975-0975(Online); 0376-4710(Print)
Appears in Collections:IJC-A Vol.50A(03-04) [March-April 2011]

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