Charged Residues at the First Transmembrane Region Contribute to the Voltage Dependence of the Slow Gate of Connexins

Pinto, Bernardo I.; García, Isaac E.; Pupo, Amaury; Retamal, Mauricio A.; Martı́nez, Agustı́n D.; Latorre, Ramón; González, Carlos

doi:10.1074/jbc.m115.709402

Cited by 13 publications

(23 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Experimental evidence indicates mutagenesis of R75, K41 and E42 significantly alters Cx26 voltage sensitivity (60,77,78). In particular, K41 neutralization results in an increase of the gating charge, while the double mutant K41E/E42S was shown to be more sensitive to voltage than the wild type (60). While experimental evidence suggests D2 to also contribute to voltage sensitivity (61), this residue did not exhibit any large ; value in our analysis.…”

Section: Resultscontrasting

confidence: 63%

“…4). Many of these residues have already been suggested to play crucial roles in voltage sensitivity (60,62,(77)(78)(79). For instance, molecular dynamics simulations (62,79) suggested an electrostatic network between E42, D46, R75, R184, E187 and K188 to be a part of the voltage sensor.…”

Section: Resultsmentioning

confidence: 99%

“…For instance, molecular dynamics simulations (62,79) suggested an electrostatic network between E42, D46, R75, R184, E187 and K188 to be a part of the voltage sensor. Experimental evidence indicates mutagenesis of R75, K41 and E42 significantly alters Cx26 voltage sensitivity (60,77,78). In particular, K41 neutralization results in an increase of the gating charge, while the double mutant K41E/E42S was shown to be more sensitive to voltage than the wild type (60).…”

Section: Resultsmentioning

confidence: 99%

“…In most other VSMPs, the voltage-sensing elements are nowhere near as well characterized. Several studies suggest different origins of their voltage sensitivity, including specific protein residues and/or ions trapped inside protein cavities (8,9,(60)(61)(62)(63)(64)(65)(66)(67). Ions moving in an electric field have for instance been suggested to trigger conformational rearrangements in voltage-gated chloride channels (66,(68)(69)(70), solute carriers (10), active transporters (8,9,71,72) and G-protein coupled receptors (67).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Molecular basis for voltage sensitivity in membrane proteins

Lindahl

Delemotte

2018

Preprint

View full text Add to dashboard Cite

Voltage-sensitive membrane proteins are united by the ability to transform changes in the membrane potential into mechanical work. They are responsible for a spectrum of key physiological processes in living organisms, including electric signaling and progression along the cell cycle. While the voltage-sensing mechanism has been well characterized for some membrane proteins such as voltage-gated ion channels, for others even the location of the voltage-sensing elements remains unknown. The detection of these elements using experimental techniques is complicated due to the large diversity of membrane proteins. Here, we suggest a computational approach to predict voltage-sensing elements in any membrane protein independent of structure or function. It relies on the estimation of the capacity of a protein to respond to changes in the membrane potential. We first show how this property correlates well with voltage sensitivity by applying our approach to a set of membrane proteins including voltage-sensitive and voltage-insensitive ones. We further show that it correctly identifies true voltagesensitive residues in the voltage sensor domain of voltage-gated ion channels. Finally, we investigate six membrane proteins for which the voltage-sensing elements have not yet been characterized and identify residues and ions potentially involved in the response to voltage. The suggested approach is fast and simple and allows for characterization of voltage sensitivity that goes beyond mere identification of charges. We anticipate that its application prior to mutagenesis experiments will allow for significant reduction of the number of potential voltage-sensitive elements to be tested.

show abstract

Section: Resultscontrasting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Molecular basis for voltage sensitivity in membrane proteins

Lindahl

Delemotte

2018

Preprint

View full text Add to dashboard Cite

show abstract

“…A recent study has shown that voltage-dependence of the slow gate is located at charged residues of the first-transmembrane region of Cx46 as well as Cx26 and Cx50 (36). It is plausible that the mutation of G143 site may alter the conformation of the voltage sensor of Cx46, most likely through the interaction of C-terminus, the second aforementioned mechanism.…”

Section: Discussionmentioning

confidence: 99%

Cataract-associated connexin 46 mutation alters its interaction with calmodulin and function of hemichannels

Riquelme²,

Wang

et al. 2018

Journal of Biological Chemistry

View full text Add to dashboard Cite

Connexin channels help maintain eye lens homeostasis and transparency. The G143R missense substitution in connexin (Cx) 46 is associated with congenital Coppock cataracts; however, the underlying molecular mechanism is largely unknown. Here, we report that compared with wild type (WT) Cx46, the G143R substitution abolishes hemichannel conductance in Xenopus oocytes and in HeLa cells. Moreover, this substitution is dominant-negative and inhibits conductance of WT Cx46. CD analysis indicated that the substitution greatly reduces the α-helical structure of the intracellular Cx46 loop domain. Protein pulldown assays and isothermal titration calorimetry (ITC) revealed that this Cx46 domain directly interacts with calmodulin (CaM) in a Ca 2+ -dependent fashion, an observation confirmed by immunofluorescent co-localization of Cx46 with CaM. Interestingly, the G143R substitution enhanced the Cx46-CaM interaction and attenuated its abolishment by Ca 2+ depletion. Moreover, Cx46 increased dye influx, and the G143R substitution augmented this effect. Inhibition of Ca 2+ -mediated CaM activation blocked hemichannel permeability. The membrane potential plays a crucial role in Cx46 membrane permeability. We found that the activity of hemichannels is detectable under rest and hyperpolarization conditions, but is eliminated with depolarization. These results suggested that the G143R substitution impairs voltage-dependent electrical conductance and alters membrane permeability mediated by Cx46 hemichannels. The latter likely is caused by the substitution-induced structural changes of the intracellular loop domain associated with the increased interaction with CaM and reduced Ca 2+ sensitivity. The data suggest that the G143R-induced enhancement of the CaMCx46 interaction results in altered hemichannel activities and might be related to cataract formation.The lens is a clear part of the anterior eye that focuses light and images onto the retina. Cataracts, referring to the clouding of the lens, are responsible for 51% of world blindness according to WHO data in 2010 (1). The lens has three main parts; the capsule, the epithelial layer in the anterior portion, and fiber cells which comprise the bulk of lens (2). Lens fiber cells communicate to each other and to the surface of the lens by gap junction channels and hemichannels. These allow small molecules (< 1.2 kDa) like ions, second messenger and metabolites to pass through adjacent cells (3-5). Lens is an avascular organ and thus relies in part upon gap junction channels and hemichannels to maintain its metabolic homeostasis and transparency. Hemichannels, also called connexins, are undocked http://www.jbc.org/cgi

show abstract

References

2019

Gap Junction Structure and Chemical Regulation

View full text Add to dashboard Cite

Charged Residues at the First Transmembrane Region Contribute to the Voltage Dependence of the Slow Gate of Connexins

Cited by 13 publications

References 55 publications

Molecular basis for voltage sensitivity in membrane proteins

Molecular basis for voltage sensitivity in membrane proteins

Cataract-associated connexin 46 mutation alters its interaction with calmodulin and function of hemichannels

References

Contact Info

Product

Resources

About