TY  - THES
AU  - Cukkemane, Abhishek
TI  - Structural and functional studies of a prokaryotic cyclic nucleotide-gated channel
VL  - 4270
IS  - Juel-4270
SN  - 0944-2952
PB  - Univ. Köln
VL  - Dr. (Univ.)
CY  - Jülich
M1  - PreJuSER-1301
M1  - Juel-4270
T2  - Berichte des Forschungszentrums Jülich
SP  - VIII, 114 p.
PY  - 2008
N1  - Record converted from VDB: 12.11.2012
N1  - Köln, Univ., Diss., 2007
AB  - Ion channels gated by cyclic nucleotides have crucial roles in cardiac and neuronal excitability and in signal transduction of sensory neurons. On binding cyclic nucleotides these channels are activated, which results an increase in membrane conductance. Although a lot of information is available on the function of these channel proteins, the molecular events that relay ligand binding to channel activation is not well understood. Here, I studied ligand binding of prokaryotic cyclic nucleotide-activated K$^{+}$ channels. One of them, the mlCNG channel from the nitrogen-fixing bacterium Mesorhizobium loti was suitable for biophysical characterization. One of the key questions that I worked on was how gating of the channel affects its ligand binding properties? I performed ligand binding studies on the tetrameric mlCNG protein and its isolated cyclic nucleotide-binding domain (CNBD). Affinity of cyclic nucleotides to the full-length mlCNG protein and to the CNBD was determined using spectroscopic methods. Both, the mlCNG channel and the CNBD bind cAMP in a non-cooperative manner with similar binding affinity. These results indicate that either no appreciable binding energy is required for activation, or the conformational change in the CNBD is the activation step itself. Crystallography experiments were performed on the mlCNG channel. Two-dimensional crystals were obtained in which the channel proteins were ordered in a square lattice. The channel proteins were assembled as tetramers and were arranged in a head-to tail fashion. The crystal diffracts to 15 Å. This is an excellent starting condition for future work to eventually obtain a structure at atomic resolution.
LB  - PUB:(DE-HGF)11 ; PUB:(DE-HGF)3
UR  - https://juser.fz-juelich.de/record/1301
ER  -