3BPZ

HCN2-I 443-460 E502K in the presence of cAMP

Summary for 3BPZ

• Entry DOI: 10.2210/pdb3bpz/pdb
• Related: 1Q43
• Descriptor: Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 2, ADENOSINE-3',5'-CYCLIC-MONOPHOSPHATE (3 entities in total)
• Functional Keywords: cnbd, c-linker, pacemaker, hcn, hcn2, channel, cyclic nucleotide, cap, pka, camp, ion channel, ligand, camp-binding, glycoprotein, ion transport, ionic channel, membrane, nucleotide-binding, phosphoprotein, potassium, potassium channel, potassium transport, sodium, sodium channel, sodium transport, transmembrane, transport, voltage-gated channel, transport protein
• Biological source: Mus musculus (house mouse)
• Cellular location: Cell membrane ; Multi-pass membrane protein : O88703
• Total number of polymer chains: 4
• Total formula weight: 95829.41

Authors

Craven, K.B.,Olivier, N.B.,Zagotta, W.N. (deposition date: 2007-12-19, release date: 2008-03-25, Last modification date: 2023-08-30)

Primary citation

Craven, K.B.,Olivier, N.B.,Zagotta, W.N.
C-terminal movement during gating in cyclic nucleotide-modulated channels.
J.Biol.Chem., 283:14728-14738, 2008

PubMed Abstract: Activation of cyclic nucleotide-modulated channels such as CNG and HCN channels is promoted by ligand-induced conformational changes in their C-terminal regions. The primary intersubunit interface of these C termini includes two salt bridges per subunit, formed between three residues (one positively charged and two negatively charged amino acids) that we term the SB triad. We previously hypothesized that the SB triad is formed in the closed channel and breaks when the channel opens. Here we tested this hypothesis by dynamically manipulating the SB triad in functioning CNGA1 channels. Reversing the charge at positions Arg-431 and Glu-462, two of the SB triad residues, by either mutation or application of charged reagents increased the favorability of channel opening. To determine how a charge reversal mutation in the SB triad structurally affects the channel, we solved the crystal structure of the HCN2 C-terminal region with the equivalent E462R mutation. The backbone structure of this mutant was very similar to that of wild type, but the SB triad was rearranged such that both salt bridges did not always form simultaneously, suggesting a mechanism for the increased ease of opening of the mutant channels. To prevent movement in the SB triad, we tethered two components of the SB triad region together with cysteine-reactive cross-linkers. Preventing normal movement of the SB triad region with short cross-linkers inhibited channel opening, whereas longer cross-linkers did not. These results support our hypothesis that the SB triad forms in the closed channel and indicate that this region expands as the channel opens.

PubMed: 18367452
DOI: 10.1074/jbc.M710463200

Experimental method

X-RAY DIFFRACTION (1.65 Å)