3co2

Publication Abstract from PubMed

MlotiK1 is a prokaryotic homolog of cyclic-nucleotide-dependent ion channels that contains an intracellular C-terminal cyclic nucleotide binding (CNB) domain. X-ray structures of the CNB domain have been solved in the absence of ligand and bound to cAMP. Both the full-length channel and CNB domain fragment are easily expressed and purified, making MlotiK1 a useful model system for dissecting activation by ligand binding. We have used X-ray crystallography to determine three new MlotiK1 CNB domain structures: a second apo configuration, a cGMP-bound structure, and a second cAMP-bound structure. In combination, the five MlotiK1 CNB domain structures provide a unique opportunity for analyzing, within a single protein, the structural differences between the apo state and the bound state, and the structural variability within each state. With this analysis as a guide, we have probed the nucleotide selectivity and importance of specific residue side chains in ligand binding and channel activation. These data help to identify ligand-protein interactions that are important for ligand dependence in MlotiK1 and, more globally, in the class of nucleotide-dependent proteins.

Structural and energetic analysis of activation by a cyclic nucleotide binding domain.,Altieri SL, Clayton GM, Silverman WR, Olivares AO, De la Cruz EM, Thomas LR, Morais-Cabral JH J Mol Biol. 2008 Sep 5;381(3):655-69. Epub 2008 Jun 10. PMID:18619611^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.