Intrinsic gating mechanisms of epithelial sodium channels

2002 ◽  
Vol 283 (2) ◽  
pp. C646-C650 ◽  
Author(s):  
Hong-Long Ji ◽  
Catherine M. Fuller ◽  
Dale J. Benos
Keyword(s):  
Sodium Channels ◽  
Xenopus Oocytes ◽  
Transmembrane Domain ◽  
Receptor Site ◽  
Epithelial Sodium Channels ◽  
Gating Mechanisms ◽  
Putative Receptor ◽  
Arginine Residues ◽  
Insight Into ◽  
Positively Charged

The hypothesis that there is a highly conserved, positively charged region distal to the second transmembrane domain in α-ENaC (epithelial sodium channel) that acts as a putative receptor site for the negatively charged COOH-terminal β- and γ-ENaC tails was tested in mutagenesis experiments. After expression in Xenopus oocytes, α-ENaC constructs in which positively charged arginine residues were converted into negatively charged glutamic acids could not be inhibited by blocking peptides. These observations provide insight into the gating machinery of ENaC.

scholarly journals Arginine mutations within a transmembrane domain of Tar, an Escherichia coli aspartate receptor, can drive homodimer dissociation and heterodimer association in vivo

2004 ◽  
Vol 385 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Neta SAL-MAN ◽  
Yechiel SHAI
Keyword(s):  
Amino Acids ◽  
Transmembrane Domain ◽  
Genetic Diseases ◽  
Ion Pairs ◽  
Aspartate Receptor ◽  
Charged Residues ◽  
Arginine Residues ◽  
Tm Domain ◽  
Positively Charged

The interactions between the TM (transmembrane) domains of many membrane proteins are important for their proper functioning. Mutations of residues into positively charged ones within TM domains were reported to be involved in many genetic diseases, possibly because these mutations affect the self- and/or hetero-assembly of the corresponding proteins. To our knowledge, despite significant progress in understanding the role of various amino acids in TM–TM interactions in vivo, the direct effect of positively charged residues on these interactions has not been studied. To address this issue, we employed the N-terminal TM domain of the aspartate receptor (Tar-1) as a dimerization model system. We expressed within the ToxR TM assembly system several Tar-1 constructs that dimerize via polar- or non-polar amino acid motifs, and mutated these by replacement with a single arginine residue. Our results have revealed that a mutation in each of the motifs significantly reduced the ability of the TMs to dimerize. Furthermore, a Tar-1 construct that contained two arginine residues was unable to correctly integrate itself into the membrane. Nevertheless, an exogenous synthetic Tar-1 peptide containing these two arginine residues was able to inhibit in vivo the marked dimerization of a mutant Tar-1 construct that contained two glutamate residues at similar positions. This indicates that hetero-assembly of TM domains can be mediated by the interaction of two oppositely charged residues, probably by formation of ion pairs. This study broadens our knowledge regarding the effect of positively charged residues on TM–TM interactions in vivo, and provides a potential therapeutic approach to inhibit uncontrolled dimerization of TM domains caused by mutations of polar amino acids.

scholarly journals Voltage-Dependent Inactivation of MscS Occurs Independently of the Positively Charged Residues in the Transmembrane Domain

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Takeshi Nomura ◽  
Masahiro Sokabe ◽  
Kenjiro Yoshimura
Keyword(s):  
Voltage Dependence ◽  
Transmembrane Domain ◽  
Wild Type ◽  
Dependent Inactivation ◽  
Mechanical Threshold ◽  
Voltage Dependent ◽  
Arginine Residues ◽  
Tm Domain ◽  
Small Conductance ◽  
Positively Charged

MscS (mechanosensitive channel of small conductance) is ubiquitously found among bacteria and plays a major role in avoiding cell lysis upon rapid osmotic downshock. The gating of MscS is modulated by voltage, but little is known about how MscS senses membrane potential. Three arginine residues (Arg-46, Arg-54, and Arg-74) in the transmembrane (TM) domain are possible to respond to voltage judging from the MscS structure. To examine whether these residues are involved in the voltage dependence of MscS, we neutralized the charge of each residue by substituting with asparagine (R46N, R54N, and R74N). Mechanical threshold for the opening of the expressed wild-type MscS and asparagine mutants did not change with voltage in the range from-40 to +100 mV. By contrast, inactivation process of wild-type MscS was strongly affected by voltage. The wild-type MscS inactivated at +60 to +80 mV but not at-60 to +40 mV. The voltage dependence of the inactivation rate of all mutants tested, that is, R46N, R54N, R74N, and R46N/R74N MscS, was almost indistinguishable from that of the wild-type MscS. These findings indicate that the voltage dependence of the inactivation occurs independently of the positive charges of R46, R54, and R74.

scholarly journals Block of Brain Sodium Channels by Peptide Mimetics of the Isoleucine, Phenylalanine, and Methionine (IFM) Motif from the Inactivation Gate

1999 ◽  
Vol 113 (2) ◽  
pp. 279-294 ◽  
Author(s):  
Galen Eaholtz ◽  
Anita Colvin ◽  
Daniele Leonard ◽  
Charles Taylor ◽  
William A. Catterall
Keyword(s):  
Amino Acid ◽  
Sodium Channels ◽  
Receptor Site ◽  
Amino Acid Residues ◽  
Intracellular Loop ◽  
Hydrophobic Residues ◽  
Inactivation Process ◽  
Effective Use ◽  
Cytoplasmic Side ◽  
Positively Charged

Inactivation of sodium channels is thought to be mediated by an inactivation gate formed by the intracellular loop connecting domains III and IV. A hydrophobic motif containing the amino acid sequence isoleucine, phenylalanine, and methionine (IFM) is required for the inactivation process. Peptides containing the IFM motif, when applied to the cytoplasmic side of these channels, produce two types of block: fast block, which resembles the inactivation process, and slow, use-dependent block stimulated by strong depolarizing pulses. Fast block by the peptide ac-KIFMK-NH2, measured on sodium channels whose inactivation was slowed by the α-scorpion toxin from Leiurus quinquestriatus (LqTx), was reversed with a time constant of 0.9 ms upon repolarization. In contrast, control and LqTx-modified sodium channels were slower to recover from use-dependent block. For fast block, linear peptides of three to six amino acid residues containing the IFM motif and two positive charges were more effective than peptides with one positive charge, whereas uncharged IFM peptides were ineffective. Substitution of the IFM residues in the peptide ac-KIFMK-NH2 with smaller, less hydrophobic residues prevented fast block. The positively charged tripeptide IFM-NH2 did not cause appreciable fast block, but the divalent cation IFM-NH(CH2)2NH2 was as effective as the pentapeptide ac-KIFMK-NH2. The constrained peptide cyclic KIFMK containing two positive charges did not cause fast block. These results indicate that the position of the positive charges is unimportant, but flexibility or conformation of the IFM-containing peptide is important to allow fast block. Slow, use-dependent block was observed with IFM-containing peptides of three to six residues having one or two positive charges, but not with dipeptides or phenylalanine-amide. In contrast to its lack of fast block, cyclic KIFMK was an effective use-dependent blocker. Substitutions of amino acid residues in the tripeptide IFM-NH2 showed that large hydrophobic residues are preferred in all three positions for slow, use-dependent block. However, substitution of the large hydrophobic residue diphenylalanine or the constrained residues phenylglycine or tetrahydroisoquinoline for phe decreased potency, suggesting that this phe residue must be able to enter a restricted hydrophobic pocket during the binding of IFM peptides. Together, the results on fast block and slow, use-dependent block indicate that IFM peptides form two distinct complexes of different stability and structural specificity with receptor site(s) on the sodium channel. It is proposed that fast block represents binding of these peptides to the inactivation gate receptor, while slow, use-dependent block represents deeper binding of the IFM peptides in the pore.

Epithelial sodium channels expressed in Xenopus oocytes are activated by cyclic-AMP

2002 ◽  
Vol 6 (4) ◽  
pp. 195-201 ◽  
Author(s):  
K. Tamba ◽  
Y. S. Oh ◽  
J. K. Tucker ◽  
M. W. Quick ◽  
D. G. Warnock
Keyword(s):  
Cyclic Amp ◽  
Sodium Channels ◽  
Xenopus Oocytes ◽  
Epithelial Sodium Channels

Medullary epithelial sodium channels (ENAC) participate in cerebral blood flow (CBF) autoregulation

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S190-S190
Author(s):  
Eugene Golanov ◽  
Heather Drummond ◽  
Jasleen Shant ◽  
Benjamin Clower ◽  
Betty Chen
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Sodium Channels ◽  
Epithelial Sodium Channels

scholarly journals Structural analysis of cross α-helical nanotubes provides insight into the designability of filamentous peptide nanomaterials

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Fengbin Wang ◽  
Ordy Gnewou ◽  
Charles Modlin ◽  
Leticia C. Beltran ◽  
Chunfu Xu ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Synthetic Peptide ◽  
Quaternary Structure ◽  
De Novo ◽  
Rational Approach ◽  
Lateral Interactions ◽  
Protein Assemblies ◽  
Self Assembling ◽  
Arginine Residues ◽  
Insight Into

AbstractThe exquisite structure-function correlations observed in filamentous protein assemblies provide a paradigm for the design of synthetic peptide-based nanomaterials. However, the plasticity of quaternary structure in sequence-space and the lability of helical symmetry present significant challenges to the de novo design and structural analysis of such filaments. Here, we describe a rational approach to design self-assembling peptide nanotubes based on controlling lateral interactions between protofilaments having an unusual cross-α supramolecular architecture. Near-atomic resolution cryo-EM structural analysis of seven designed nanotubes provides insight into the designability of interfaces within these synthetic peptide assemblies and identifies a non-native structural interaction based on a pair of arginine residues. This arginine clasp motif can robustly mediate cohesive interactions between protofilaments within the cross-α nanotubes. The structure of the resultant assemblies can be controlled through the sequence and length of the peptide subunits, which generates synthetic peptide filaments of similar dimensions to flagella and pili.

scholarly journals The Plant-Derived Glucocorticoid Receptor Agonist Endiandrin A Acts as Co-Stimulator of Colonic Epithelial Sodium Channels (ENaC) via SGK-1 and MAPKs

PLoS ONE ◽  
2012 ◽  
Vol 7 (11) ◽  
pp. e49426 ◽  
Author(s):  
Dana Kuntzsch ◽  
Theresa Bergann ◽  
Petra Dames ◽  
Anja Fromm ◽  
Michael Fromm ◽  
...  
Keyword(s):  
Glucocorticoid Receptor ◽  
Sodium Channels ◽  
Receptor Agonist ◽  
Epithelial Sodium Channels

scholarly journals Proteolytic Regulation of Epithelial Sodium Channels by Urokinase Plasminogen Activator

2015 ◽  
Vol 290 (9) ◽  
pp. 5241-5255 ◽  
Author(s):  
Hong-Long Ji ◽  
Runzhen Zhao ◽  
Andrey A. Komissarov ◽  
Yongchang Chang ◽  
Yongfeng Liu ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Sodium Channels ◽  
Urokinase Plasminogen Activator ◽  
Epithelial Sodium Channels

scholarly journals Ethanol Alters Alveolar Fluid Balance via Nadph Oxidase (NOX) Signaling to Epithelial Sodium Channels (ENaC) in the Lung

PLoS ONE ◽  
2013 ◽  
Vol 8 (1) ◽  
pp. e54750 ◽  
Author(s):  
Charles A. Downs ◽  
David Q. Trac ◽  
Lisa H. Kreiner ◽  
Amity F. Eaton ◽  
Nicholle M. Johnson ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Sodium Channels ◽  
Fluid Balance ◽  
Epithelial Sodium Channels
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