Structural and energetic analysis of activation by a cyclic nucleotide binding domain

JOURNAL OF MOLECULAR BIOLOGY

卷:381

Article

Altieri, Stephen L.¹  Clayton, Gina M.¹  Silverman, William R.¹  Olivares, Adrian O.¹  De La Cruz, Enrique M.¹  Thomas, Lise R.¹  Morais-Cabral, Joao H.¹ 

[1] Yale Univ, Dept Mol Biophys & Biochem, New Haven, CT 06520 USA

关键词: Mesorhizobium loti;    potassium channel;    ligand-dependent gating;    cyclic nucleotide;    conformational variability;   

DOI  :  10.1016/j.jmb.2008.06.011

来源: Elsevier

【 摘 要 】

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 Xray 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. (C) 2008 Elsevier Ltd. All rights reserved.

【 授权许可】

Free