Role of gamma carboxylated Glu47 in connexin 26 hemichannel regulation by extracellular Ca2+: Insight from a local quantum chemistry study

Zonta, Francesco; Mammano, Fabio; Torsello, Mauro; Fortunati, Nicola; Orian, Laura; Polimeno, Antonino

doi:10.1016/j.bbrc.2014.01.063

Cited by 22 publications

(19 citation statements)

References 38 publications

(37 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is important to also notice that the interaction of GLU47 and calcium was studied by the means of quantum chemistry methods by Zonta et al [61]. Through their calculations, the researchers explored GLU47, ARG75 and ARG184 with Ca 2+ in a Cx26 hemichannel and their results proved that the post-translational glutamate GLU47 is a strong candidate to bind Ca 2+ in the extracellular side on Cx26.…”

Section: Resultsmentioning

confidence: 99%

Calcium interactions with Cx26 hemmichannel: Spatial association between MD simulations biding sites and variant pathogenicity

Albano

Mussini

Toriano

et al. 2018

Computational Biology and Chemistry

View full text Add to dashboard Cite

Connexinophaties are a collective of diseases related to connexin channels and hemichannels. In particular many Cx26 alterations are strongly associated to human deafness. Calcium plays an important role on this structures regulation. Here, using calcium as a probe, extensive atomistic Molecular Dynamics simulations were performed on the Cx26 hemichannel embedded in a lipid bilayer. Exploring different initial conditions and calcium concentration, simulation reached ~4 μs. Several analysis were carried out in order to reveal the calcium distribution and localization, such as electron density profiles, density maps and distance time evolution, which is directly associated to the interaction energy. Specific amino acid interactions with calcium and their stability were capture within this context. Few of these sites such as, GLU42, GLU47, GLY45 and ASP50, were already suggested in the literature. Besides, we identified novel calcium biding sites: ASP2, ASP117, ASP159, GLU114, GLU119, GLU120 and VAL226. To the best of our knowledge, this is the first time that these sites are reported within this context. Furthermore, since various pathologies involving the Cx26 hemichannel are associated with pathogenic variants in the corresponding CJB2 gene, using ClinVar, we were able to spatially associate the 3D positions of the identified calcium binding sites within the framework of this work with reported pathogenic variants in the CJB2 gene. This study presents a first step on finding associations between molecular features and pathological variants of the Cx26 hemichannel.

show abstract

Section: Resultsmentioning

confidence: 99%

Calcium interactions with Cx26 hemmichannel: Spatial association between MD simulations biding sites and variant pathogenicity

Albano

Mussini

Toriano

et al. 2018

Computational Biology and Chemistry

View full text Add to dashboard Cite

show abstract

“…Calcium is a central regulator of keratinocyte differentiation, thus the disruption of calcium hemostasis often results in KID ( Elsholz et al, 2014 ). The p.Gly45 amino acid is located in the first Cx26 extracellular loop (E1) adjacent to p.Glu47 where they are two of the three aminoacids involved in the Ca 2+ binding site for Cx26 gap junction hemichannels ( Bennett et al, 2016 ; Kwon, Tang & Bargiello, 2013 ; Zonta et al, 2014 ). The p.Gly45Glu variant substitutes a negatively charged (acidic) amino acid for a nonpolar one, affecting its localization and interfering with Ca 2+ regulation of hemichannel gating ( Sánchez et al, 2010 ).…”

Section: Discussionmentioning

confidence: 99%

“…The missense variant c.134G>A (p.Gly45Glu) in GJB2 exon 2 is associated with the keratitis-ichthyosis-deafness (KID) syndrome, which is often fatal in the first year of life because of cutaneous infections and septicemia ( Janecke et al, 2005 ). The glycine at position 45 is a highly conserved amino acid across all major connexins ( Zhang & Hao, 2013 ) and its location in the parahelix region (residues 42–50) near the highly conserved Ca 2+ binding amino acids p.Gly45, p.Asp46 and p.Glu47 makes p.Gly45 important in the voltage-dependent loop-gate permeability barrier in Cx26 ( Kwon, Tang & Bargiello, 2013 ; Zonta et al, 2014 ; Bennett et al, 2016 ). Interestingly, in the Japanese population p.Gly45Glu is usually associated with p.Tyr136Stop (c.408C>A) in cis (p.Gly45Glu with p.Tyr136Stop).…”

Section: Introductionmentioning

confidence: 99%

Comparative functional characterization of novel non-syndromicGJB2gene variant p.Gly45Arg and lethal syndromic variant p.Gly45Glu

Rodriguez-Paris

Waldhaus

Gordhandas

et al. 2016

PeerJ

View full text Add to dashboard Cite

We characterized a novel GJB2 missense variant, c.133G>A, p.Gly45Arg, and compared it with the only other variant at the same amino acid position of the connexin 26 protein (Cx26) reported to date: c.134G>A, p.Gly45Glu. Whereas both variants are associated with hearing loss and are dominantly inherited, p.Gly45Glu has been implicated in the rare fatal keratitis-ichthyosis-deafness (KID) syndrome, which results in cutaneous infections and septicemia with premature demise in the first year of life. In contrast, p.Gly45Arg appears to be non-syndromic. Subcellular localization experiments in transiently co-transfected HeLa cells demonstrated that Cx26-WT (wild-type) and p.Gly45Arg form gap junctions, whereas Cx26-WT with p.Gly45Glu protein does not. The substitution of a nonpolar amino acid glycine in wildtype Cx26 at position 45 with a negatively charged glutamic acid (acidic) has previously been shown to interfere with Ca2+ regulation of hemichannel gating and to inhibit the formation of gap junctions, resulting in cell death. The novel variant p.Gly45Arg, however, changes this glycine to a positively charged arginine (basic), resulting in the formation of dysfunctional gap junctions that selectively affect the permeation of negatively charged inositol 1,4,5-trisphosphate (IP3) and contribute to hearing loss. Cx26 p.Gly45Arg transfected cells, unlike cells transfected with p.Gly45Glu, thrived at physiologic Ca2+ concentrations, suggesting that Ca2+ regulation of hemichannel gating is unaffected in Cx26 p.Gly45Arg transfected cells. Thus, the two oppositely charged amino acids that replace the highly conserved uncharged glycine in p.Gly45Glu and p.Gly45Arg, respectively, produce strikingly different effects on the structure and function of the Cx26 protein.

show abstract

“…Quantum chemistry computations performed by Zonta et al . had also suggested that Ca 2+ binds to the ɤ-carboxylated E47, altering the local structure of the Cx26 hemichannel and preventing stabilizing interactions with R75 from the same monomer and R184 from an adjacent monomer 71 . These studies differ in the proposed mechanisms of Ca 2+ -dependent block: Bennett et al .…”

Section: Structural Insights Into Channel Gatingmentioning

confidence: 99%

“…suggested that binding of calcium ions generates an electrostatic barrier that inhibits the permeation of cations through the pore 22 ; in contrast, Zonta et al . proposed that extracellular Ca 2+ binding produces structural alterations 71 . It is unclear whether the Ca 2+ electrostatic barrier mechanism (which does not produce steric occlusion of the pore) or the structural alterations (obtained by quantum chemistry computations) could explain loop gating.…”

Section: Structural Insights Into Channel Gatingmentioning

confidence: 99%

Gap junction structure: unraveled, but not fully revealed

Beyer

Berthoud

2017

F1000Res

View full text Add to dashboard Cite

Gap junction channels facilitate the intercellular exchange of ions and small molecules, a process that is critical for the function of many different kinds of cells and tissues. Recent crystal structures of channels formed by one connexin isoform (connexin26) have been determined, and they have been subjected to molecular modeling. These studies have provided high-resolution models to gain insights into the mechanisms of channel conductance, molecular permeability, and gating. The models share similarities, but there are some differences in the conclusions reached by these studies. Many unanswered questions remain to allow an atomic-level understanding of intercellular communication mediated by connexin26. Because some domains of the connexin polypeptides are highly conserved (like the transmembrane regions), it is likely that some features of the connexin26 structure will apply to other members of the family of gap junction proteins. However, determination of high-resolution structures and modeling of other connexin channels will be required to account for the diverse biophysical properties and regulation conferred by the differences in their sequences.

show abstract

Role of gamma carboxylated Glu47 in connexin 26 hemichannel regulation by extracellular Ca2+: Insight from a local quantum chemistry study

Abstract: Graphical abstract

Cited by 22 publications

References 38 publications

Calcium interactions with Cx26 hemmichannel: Spatial association between MD simulations biding sites and variant pathogenicity

Calcium interactions with Cx26 hemmichannel: Spatial association between MD simulations biding sites and variant pathogenicity

Comparative functional characterization of novel non-syndromicGJB2gene variant p.Gly45Arg and lethal syndromic variant p.Gly45Glu

Gap junction structure: unraveled, but not fully revealed

Contact Info

Product

Resources

About