Tryptophan 207 is crucial to the unique properties of the human voltage-gated proton channel, hHV1

Cherny, Vladimir V.; Morgan, Deri; Musset, Boris; Chaves, Gustavo; Smith, Susan; DeCoursey, Thomas E.

doi:10.1085/jgp.201511456

Cited by 44 publications

(68 citation statements)

References 54 publications

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“…Similar to Hv1 (Cherny et al . ), ΔpH sensing in Hv1Sper appears to saturate at alkaline pH: at both extracellular and intracellular pH 8, the V 1/2 shifted only by ∼20 mV/pH unit (Fig. E ).…”

Section: Resultsmentioning

confidence: 87%

Post‐translational cleavage of Hv1 in human sperm tunes pH‐ and voltage‐dependent gating

Berger

Fußhöller

Goodwin

et al. 2017

The Journal of Physiology

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In human sperm, the voltage-gated proton channel Hv1 controls the flux of protons across the flagellar membrane. Here, we show that sperm harbour Hv1 and a shorter isoform, termed Hv1Sper. Hv1Sper is generated from Hv1 by removal of 68 amino acids from the N-terminus by post-translational proteolytic cleavage. The pH-dependent gating of the channel isoforms is distinctly different. In both Hv1 and Hv1Sper, the conductance-voltage relationship is determined by the pH difference across the membrane (∆pH). However, simultaneous changes in intracellular and extracellular pH that leave ΔpH constant strongly shift the activation curve of Hv1Sper but not that of Hv1, demonstrating that cleavage of the N-terminus tunes pH sensing in Hv1. Moreover, we show that Hv1 and Hv1Sper assemble as heterodimers that combine features of both constituents. We suggest that cleavage and heterodimerization of Hv1 represents an adaptation to the specific requirements of pH control in sperm.

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Section: Resultsmentioning

confidence: 87%

Post‐translational cleavage of Hv1 in human sperm tunes pH‐ and voltage‐dependent gating

Berger

Fußhöller

Goodwin

et al. 2017

The Journal of Physiology

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“…This is an unexpected result, considering that the data also indicate that the gating current kinetics is defined by multiple states (41). However, the lack of a well-defined Cole-Moore effect may be due to the fast activation kinetics conferred by the W207A mutation (42).…”

Section: Methodsmentioning

confidence: 86%

Gating charge displacement in a monomeric voltage-gated proton (H _v 1) channel

Carmona

Larsson

Neely

et al. 2018

Proc. Natl. Acad. Sci. U.S.A.

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The voltage-gated proton (H1) channel, a voltage sensor and a conductive pore contained in one structural module, plays important roles in many physiological processes. Voltage sensor movements can be directly detected by measuring gating currents, and a detailed characterization of H1 charge displacements during channel activation can help to understand the function of this channel. We succeeded in detecting gating currents in the monomeric form of the -H1 channel. To decrease proton currents and better separate gating currents from ion currents, we used the low-conducting H1 mutant N264R. Isolated ON-gating currents decayed at increasing rates with increasing membrane depolarization, and the amount of gating charges displaced saturates at high voltages. These are two hallmarks of currents arising from the movement of charged elements within the boundaries of the cell membrane. The kinetic analysis of gating currents revealed a complex time course of the ON-gating current characterized by two peaks and a marked Cole-Moore effect. Both features argue that the voltage sensor undergoes several voltage-dependent conformational changes during activation. However, most of the charge is displaced in a single central transition. Upon voltage sensor activation, the charge is trapped, and only a fast component that carries a small percentage of the total charge is observed in the OFF. We hypothesize that trapping is due to the presence of the arginine side chain in position 264, which acts as a blocking ion. We conclude that the movement of the voltage sensor must proceed through at least five states to account for our experimental data satisfactorily.

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“…The resulting cation-π interaction was proposed to explain why proton flux into the virion is much smaller than the His-water proton exchange rate [29]. Similar aromatic interactions have been proposed for the H v 1 channel between W207 and R211 [12], where W207 controls the gating kinetics, conduction activation energy, and the pH dependence of gating.…”

Section: Introductionmentioning

confidence: 93%

“…This HxxxW motif is conserved among all influenza A and B viruses’ M2 sequences [2]. Asymmetric ion conduction is also known for some voltage-gated potassium channels, which use cytoplasmic factors such as polyamines to achieve inward rectification [9–11], and in voltage-gated proton channels of the H v 1 family, which use a conserved RxWRxxR motif to achieve inward rectification [12]. While pH-gated channels are often also voltage-gated in vivo [13], and whole-cell electrophysiological measurements of M2 proton conductance are carried out under both voltage and pH control, M2 is specifically activated by low pH of the external solution [14, 15].…”

Section: Introductionmentioning

confidence: 99%

Structural Basis for Asymmetric Conductance of the Influenza M2 Proton Channel Investigated by Solid-State NMR Spectroscopy

Mandala

Liao

Kwon

et al. 2017

Journal of Molecular Biology

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The influenza M2 protein forms an acid-activated proton channel that is essential for virus replication. The transmembrane H37 selects for protons under low external pH (pHout) while W41 ensures proton conduction only from the N-terminus to the C-terminus and prevents reverse current under low internal pH (pHin). Here we address the molecular basis for this asymmetric conduction by investigating the structure and dynamics of a mutant channel, W41F, which permits reverse current under low pHin. Solid-state NMR experiments show that W41F M2 retains the pH-dependent α-helical conformations and tetrameric structure of the wild-type channel, but has significantly altered protonation and tautomeric equilibria at H37. At high pH, the H37 structure is shifted towards the π tautomer and less cationic tetrads, consistent with faster forward deprotonation to the C-terminus. At low pH, the mutant channel contains more cationic tetrads than the wild-type channel, consistent with faster reverse protonation from the C-terminus. 15N NMR spectra allow the extraction of four H37 pKa’s and show that the pKa’s are more clustered in the mutant channel compared to wild-type M2. Moreover, binding of the antiviral drug, amantadine, at the N-terminal pore at low pH did not convert all histidines to the neutral state, as seen in wild-type M2, but left half of all histidines cationic, unambiguously demonstrating C-terminal protonation of H37 in the mutant. These results indicate that asymmetric conduction in wild-type M2 is due to W41 inhibition of C-terminal acid activation by H37. When Trp is replaced by Phe, protons can be transferred to H37 bidirectionally with distinct rate constants.

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Tryptophan 207 is crucial to the unique properties of the human voltage-gated proton channel, hHV1

Abstract: A conserved tryptophan uniquely present in the voltage-sensing domain of voltage-gated proton channels is surprisingly crucial to four channel-defining properties.

Cited by 44 publications

References 54 publications

Post‐translational cleavage of Hv1 in human sperm tunes pH‐ and voltage‐dependent gating

Post‐translational cleavage of Hv1 in human sperm tunes pH‐ and voltage‐dependent gating

Gating charge displacement in a monomeric voltage-gated proton (H _v 1) channel

Structural Basis for Asymmetric Conductance of the Influenza M2 Proton Channel Investigated by Solid-State NMR Spectroscopy

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Tryptophan 207 is crucial to the unique properties of the human voltage-gated proton channel, hHV1

Abstract: A conserved tryptophan uniquely present in the voltage-sensing domain of voltage-gated proton channels is surprisingly crucial to four channel-defining properties.

Cited by 44 publications

References 54 publications

Post‐translational cleavage of Hv1 in human sperm tunes pH‐ and voltage‐dependent gating

Post‐translational cleavage of Hv1 in human sperm tunes pH‐ and voltage‐dependent gating

Gating charge displacement in a monomeric voltage-gated proton (H v 1) channel

Structural Basis for Asymmetric Conductance of the Influenza M2 Proton Channel Investigated by Solid-State NMR Spectroscopy

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Gating charge displacement in a monomeric voltage-gated proton (H _v 1) channel