Structure of the connexin 26 gap junction channel at 3.5 Å resolution

Maeda, Shoji; Nakagawa, So; Suga, Michihiro; Yamashita, Eiki; Oshima, Atsunori; Fujiyoshi, Yoshinori; Tsukihara, Tomitake

doi:10.1038/nature07869

Cited by 670 publications

(1,161 citation statements)

References 56 publications

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“…Our previous mutagenesis data suggest that ATP works on Panx1 through ligand binding and R75 plays an important role in the binding because the inhibitory effect of ATP is largely decreased when R75 on the first extracellular loop of Panx1is mutated to alanine. A SCAM analysis of Panx1 [20] revealed that the permeation pathway of the Panx1 channel shares some similarity with the connexin26 channel [21] but is also distinct. The external portion of the channel pore is similar and is constructed by the amino acids from the first transmembrane segment and the first extracellular loop.…”

Section: Introductionmentioning

confidence: 99%

Alanine substitution scanning of pannexin1 reveals amino acid residues mediating ATP sensitivity

Qiu

Wang

Dahl

2011

Purinergic Signalling

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Pannexin1 is a prime candidate to represent an ATP release channel. The pannexin1 channel can be activated by extracellular ATP through purinergic receptors P2X7 or P2Y. Recent studies have shown that the Pannexin1 channel is inhibited by its own permeant ion, ATP, and also by P2X7 receptor agonists and antagonists. However, the dose dependence of this inhibition indicated that significant inhibition was prominent at ATP concentrations higher than required for activation of purinergic receptors, including P2X7 and P2Y2. The inhibitory effect of ATP is largely decreased when R75 in the first extracellular loop of Pannexin1 is mutated to alanine, indicating that ATP regulates this channel presumably through binding. To further investigate the structural property of the putative ATP binding site, we performed alanine-scanning mutagenesis of the extracellular loops of pannexin1. Mutations on W74, S237, S240, I247 and L266 in the extracellular loops 1 and 2 severely impaired the inhibitory effect of BzATP, indicating that they might be the essential amino acids in the putative binding site. Mutations on R75, S82, S93, L94, D241, S249, P259 and I267 moderately (≥50%) decreased BzATP sensitivity, suggesting their supporting roles in the binding. Mutations of other residues did not change the BzATP potency compared to wildtype except for some nonfunctional mutants. These data demonstrate that several amino acid residues on the extracellular loops of Pannexin1 mediate ATP sensitivity. Cells expressing mutant Panx1W74A exhibited an enhanced release of ATP, consistent with the removal of a negative feedback loop controlling ATP release.

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Section: Introductionmentioning

confidence: 99%

Alanine substitution scanning of pannexin1 reveals amino acid residues mediating ATP sensitivity

Qiu

Wang

Dahl

2011

Purinergic Signalling

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“…Gap junctions are multifunctional, voltage-dependent channels for the intercellular exchange of metabolites. Symmetry-constrained XRC structures disclosed two symmetric hemichannels formed by four TM helices of six protomers of connexin 26 (Maeda et al, 2009). In contrast, cryo-EC has shown asymmetric hexamers with radial outward tilting of TM helices and inside bending of the N-terminal plug of the pore (Oshima et al, 2011).…”

Section: C Pentameric Ligand-gated and Mechanosensitive Channelsmentioning

confidence: 98%

Asymmetric perturbations of signalling oligomers

Maksay

Tőke

2014

Progress in Biophysics and Molecular Biology

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This review focuses on rapid and reversible noncovalent interactions for symmetric oligomers of tetramers (voltage-gated cation channels, ionotropic glutamate receptor, CNG and CHN channels); pentameric ligand-gated and mechanosensitive channels; higher order oligomers (gap junction channel, chaperonins, proteasome, virus capsid); as well as primary and secondary transporters. In conclusion, asymmetric perturbations seem to play important functional roles in a broad range of communicating networks.

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“…This three dimensional model was built by homology using the programme MODELLER 17 and, as a template, the crystal structure of the homologous Cx26, a gap junction channel, whose structure has been determined at 3.5A resolution. 18 The two proteins share 42% of sequence identity and about 79% of sequence similarity when the cytoplasmatic region is omitted from calculation, thus the model built can be considered as trustable. The obtained structure was then submitted to different energy minimisation cycles using the programme Discover 3 from Insight II suite (Accelrys, San Diego, CA, USA), and the resulting coordinates were then used as a reliable model for visual inspection and graphical representations carried out using the programs Coot 19 and Chimera, 20 respectively.…”

Section: Molecular Modellingmentioning

confidence: 99%

Expanded spectrum of Pelizaeus–Merzbacher-like disease: literature revision and description of a novel GJC2 mutation in an unusually severe form

et al. 2012

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Homozygous or compound heterozygous mutations in the GJC2 gene, encoding the gap junction protein connexin47 (Cx47), cause the autosomal recessive hypomyelinating Pelizaeus-Merzbacher-like disease (PMLD1, MIM# 608804). Although clinical and neuroradiological findings resemble those of the classic Pelizaeus-Merzbacher disease, PMLD patients usually show a greater level of cognitive and motor functions. Unpredictably a homozygous missense GJC2 mutation (p.Glu260Lys) was found in a patient presenting with a very severe clinical picture characterised by congenital nystagmus and severe neurological impairment. Also magnetic resonance imaging was unusually severe, showing an abnormal supra-and infratentorial white matter involvement extending to the spinal cord. The novel p.Glu260Lys (c.778G4A) mutation, occurring in a highly conserved motif (SRPTEK) of the Cx47 extracellular loop-2 domain, was predicted, by modelling analysis, to break a 'salt bridge network', crucial for a proper connexin-connexin interaction to form a connexon, thus hampering the correct formation of the connexon pore. The same structural analysis, extended to the previously reported missense mutations, predicted that most changes were expected to have less severe impact on protein functions, correlating with the mild PMLD1 form of the patients. Our study expands the spectrum of PMLD1 and provides evidence that the extremely severe clinical and neuroradiological PMLD1 form of our patient likely correlates with the predicted impairment of gap junction channel assembly resulting from the detrimental effect of the new p.Glu260Lys mutant allele on Cx47 protein.

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Structure of the connexin 26 gap junction channel at 3.5 Å resolution

Cited by 670 publications

References 56 publications

Alanine substitution scanning of pannexin1 reveals amino acid residues mediating ATP sensitivity

Alanine substitution scanning of pannexin1 reveals amino acid residues mediating ATP sensitivity

Asymmetric perturbations of signalling oligomers

Expanded spectrum of Pelizaeus–Merzbacher-like disease: literature revision and description of a novel GJC2 mutation in an unusually severe form

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