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Jurkovicova-Tarabova B, Mackova K, Moravcikova L, Karmazinova M, Lacinova L. Role of individual S4 segments in gating of Ca v3.1 T-type calcium channel by voltage. Channels (Austin) 2019; 12:378-387. [PMID: 30403912 PMCID: PMC6287678 DOI: 10.1080/19336950.2018.1543520] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Contributions of voltage sensing S4 segments in domains I – IV of CaV3.1 channel to channel activation were analyzed. Neutralization of the uppermost charge in individual S4 segments by exchange of arginine for cysteine was employed. Mutant channels with single exchange in domains I – IV, in two adjacent domains, and in all four domains were constructed and expressed in HEK 293 cells. Changes in maximal gating charge Qmax and the relation between Qmax and maximal conductance Gmax were evaluated. Qmax was the most affected by single mutation in domain I and by double mutations in domains I + II and I + IV. The ratio Gmax/Qmax proportional to opening probability of the channel was significantly decreased by the mutation in domain III and increased by mutations in domains I and II. In channels containing double mutations Gmax/Qmax ratio increased significantly when the mutation in domain I was included. Mutations in domains II and III zeroed each other. Mutation in domain IV prevented the decrease caused by the mutation in domain III. Neither ion current nor gating current was observed when channels with quadruple mutations were expressed. Immunocytochemistry analysis did not reveal the presence of channel protein in the cell membrane. Likely, quadruple mutation results in a structural change that affects the channel’s trafficking mechanism. Altogether, S4 segments in domains I-IV of the CaV3.1 channel unequally contribute to channel gating by voltage. We suggest the most important role of the voltage sensor in the domain I and lesser roles of voltage sensors in domains II and III.
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Affiliation(s)
- Bohumila Jurkovicova-Tarabova
- a Center of Biosciences, Institute of Molecular Physiology and Genetics , Academy of Sciences , Bratislava , Slovakia
| | - Katarina Mackova
- a Center of Biosciences, Institute of Molecular Physiology and Genetics , Academy of Sciences , Bratislava , Slovakia
| | - Lucia Moravcikova
- a Center of Biosciences, Institute of Molecular Physiology and Genetics , Academy of Sciences , Bratislava , Slovakia
| | - Maria Karmazinova
- a Center of Biosciences, Institute of Molecular Physiology and Genetics , Academy of Sciences , Bratislava , Slovakia
| | - Lubica Lacinova
- a Center of Biosciences, Institute of Molecular Physiology and Genetics , Academy of Sciences , Bratislava , Slovakia.,b Faculty of Natural Sciences , University of Ss. Cyril and Methodius , Trnava , Slovakia
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Sanchez-Sandoval AL, Herrera Carrillo Z, Díaz Velásquez CE, Delgadillo DM, Rivera HM, Gomora JC. Contribution of S4 segments and S4-S5 linkers to the low-voltage activation properties of T-type CaV3.3 channels. PLoS One 2018; 13:e0193490. [PMID: 29474447 PMCID: PMC5825144 DOI: 10.1371/journal.pone.0193490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 02/12/2018] [Indexed: 11/25/2022] Open
Abstract
Voltage-gated calcium channels contain four highly conserved transmembrane helices known as S4 segments that exhibit a positively charged residue every third position, and play the role of voltage sensing. Nonetheless, the activation range between high-voltage (HVA) and low-voltage (LVA) activated calcium channels is around 30–40 mV apart, despite the high level of amino acid similarity within their S4 segments. To investigate the contribution of S4 voltage sensors for the low-voltage activation characteristics of CaV3.3 channels we constructed chimeras by swapping S4 segments between this LVA channel and the HVA CaV1.2 channel. The substitution of S4 segment of Domain II in CaV3.3 by that of CaV1.2 (chimera IIS4C) induced a ~35 mV shift in the voltage-dependence of activation towards positive potentials, showing an I-V curve that almost overlaps with that of CaV1.2 channel. This HVA behavior induced by IIS4C chimera was accompanied by a 2-fold decrease in the voltage-dependence of channel gating. The IVS4 segment had also a strong effect in the voltage sensing of activation, while substitution of segments IS4 and IIIS4 moved the activation curve of CaV3.3 to more negative potentials. Swapping of IIS4 voltage sensor influenced additional properties of this channel such as steady-state inactivation, current decay, and deactivation. Notably, Domain I voltage sensor played a major role in preventing CaV3.3 channels to inactivate from closed states at extreme hyperpolarized potentials. Finally, site-directed mutagenesis in the CaV3.3 channel revealed a partial contribution of the S4-S5 linker of Domain II to LVA behavior, with synergic effects observed in double and triple mutations. These findings indicate that IIS4 and, to a lesser degree IVS4, voltage sensors are crucial in determining the LVA properties of CaV3.3 channels, although the accomplishment of this function involves the participation of other structural elements like S4-S5 linkers.
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Affiliation(s)
- Ana Laura Sanchez-Sandoval
- Departamento de Neuropatología Molecular, División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Mexico City, México
| | - Zazil Herrera Carrillo
- Departamento de Neuropatología Molecular, División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Mexico City, México
| | - Clara Estela Díaz Velásquez
- Programa de Neurociencias, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla de Baz, Estado de México, México
| | - Dulce María Delgadillo
- Laboratorios Nacionales de Servicios Experimentales Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, México
| | - Heriberto Manuel Rivera
- Facultad de Medicina, Universidad Autónoma del Estado de Morelos Cuernavaca, Morelos, México
| | - Juan Carlos Gomora
- Departamento de Neuropatología Molecular, División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Mexico City, México
- * E-mail:
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Stephens RF, Guan W, Zhorov BS, Spafford JD. Selectivity filters and cysteine-rich extracellular loops in voltage-gated sodium, calcium, and NALCN channels. Front Physiol 2015; 6:153. [PMID: 26042044 PMCID: PMC4436565 DOI: 10.3389/fphys.2015.00153] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 04/28/2015] [Indexed: 12/19/2022] Open
Abstract
How nature discriminates sodium from calcium ions in eukaryotic channels has been difficult to resolve because they contain four homologous, but markedly different repeat domains. We glean clues from analyzing the changing pore region in sodium, calcium and NALCN channels, from single-cell eukaryotes to mammals. Alternative splicing in invertebrate homologs provides insights into different structural features underlying calcium and sodium selectivity. NALCN generates alternative ion selectivity with splicing that changes the high field strength (HFS) site at the narrowest level of the hourglass shaped pore where the selectivity filter is located. Alternative splicing creates NALCN isoforms, in which the HFS site has a ring of glutamates contributed by all four repeat domains (EEEE), or three glutamates and a lysine residue in the third (EEKE) or second (EKEE) position. Alternative splicing provides sodium and/or calcium selectivity in T-type channels with extracellular loops between S5 and P-helices (S5P) of different lengths that contain three or five cysteines. All eukaryotic channels have a set of eight core cysteines in extracellular regions, but the T-type channels have an infusion of 4–12 extra cysteines in extracellular regions. The pattern of conservation suggests a possible pairing of long loops in Domains I and III, which are bridged with core cysteines in NALCN, Cav, and Nav channels, and pairing of shorter loops in Domains II and IV in T-type channel through disulfide bonds involving T-type specific cysteines. Extracellular turrets of increasing lengths in potassium channels (Kir2.2, hERG, and K2P1) contribute to a changing landscape above the pore selectivity filter that can limit drug access and serve as an ion pre-filter before ions reach the pore selectivity filter below. Pairing of extended loops likely contributes to the large extracellular appendage as seen in single particle electron cryo-microscopy images of the eel Nav1 channel.
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Affiliation(s)
| | - W Guan
- Department of Biology, University of Waterloo Waterloo, ON, Canada
| | - Boris S Zhorov
- Department of Biochemistry and Biomedical Sciences, McMaster University Hamilton, ON, Canada ; Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences St. Petersburg, Russia
| | - J David Spafford
- Department of Biology, University of Waterloo Waterloo, ON, Canada
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The inhibitory effect of Ca2+-activated K+ channel activator, BMS on L-type Ca2+ channels in rat ventricular myocytes. Life Sci 2011; 89:331-6. [DOI: 10.1016/j.lfs.2011.06.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 05/10/2011] [Accepted: 06/23/2011] [Indexed: 11/22/2022]
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Li Z, Wang X, Gao G, Qu D, Yu B, Huang C, Elmslie KS, Peterson BZ. A single amino acid change in Ca(v)1.2 channels eliminates the permeation and gating differences between Ca(2+) and Ba(2+). J Membr Biol 2010; 233:23-33. [PMID: 20098982 PMCID: PMC3704197 DOI: 10.1007/s00232-009-9221-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Accepted: 12/02/2009] [Indexed: 12/22/2022]
Abstract
Glutamate scanning mutagenesis was used to assess the role of the calcicludine binding segment in regulating channel permeation and gating using both Ca(2+) and Ba(2+) as charge carriers. As expected, wild-type Ca(V)1.2 channels had a Ba(2+) conductance ~2x that in Ca(2+) (G(Ba)/G(Ca) = 2) and activation was ~10 mV more positive in Ca(2+) vs. Ba(2+). Of the 11 mutants tested, F1126E was the only one that showed unique permeation and gating properties compared to the wild type. F1126E equalized the Ca(V)1.2 channel conductance (G(Ba)/G(Ca) = 1) and activation voltage dependence between Ca(2+) and Ba(2+). Ba(2+) permeation was reduced because the interactions among multiple Ba(2+) ions and the pore were specifically altered for F1126E, which resulted in Ca(2+)-like ionic conductance and unitary current. However, the high-affinity block of monovalent cation flux was not altered for either Ca(2+) or Ba(2+). The half-activation voltage of F1126E in Ba(2+) was depolarized to match that in Ca(2+), which was unchanged from that in the wild type. As a result, the voltages for half-activation and half-inactivation of F1126E in Ba(2+) and Ca(2+) were similar to those of wild-type in Ca(2+). This effect was specific to F1126E since F1126A did not affect the half-activation voltage in either Ca(2+) or Ba(2+). These results indicate that residues in the outer vestibule of the Ca(V)1.2 channel pore are major determinants of channel gating, selectivity, and permeation.
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Affiliation(s)
- Zhe Li
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
- Department of Cardiology, Renmin Hospital and Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China
| | - Xianming Wang
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Guofeng Gao
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Dongmei Qu
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
- Department of Anesthesiology, Ruijin Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
| | - Buwei Yu
- Department of Anesthesiology, Ruijin Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai 200025, China
| | - Congxin Huang
- Department of Cardiology, Renmin Hospital and Cardiovascular Research Institute, Wuhan University, Wuhan 430060, China
| | - Keith S. Elmslie
- Departments of Anesthesiology and Pharmacology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
| | - Blaise Z. Peterson
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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Gating charges per channel of Ca(V)2.2 channels are modified by G protein activation in rat sympathetic neurons. Arch Biochem Biophys 2009; 486:51-7. [PMID: 19364492 DOI: 10.1016/j.abb.2009.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 04/01/2009] [Accepted: 04/05/2009] [Indexed: 10/20/2022]
Abstract
It has been suggested that voltage-dependent G protein modulation of Ca(V)2.2 channels is carried out at closed states of the channel. Our purpose was to estimate the number of gating charges of Ca(V)2.2 channel in control and G protein-modulated conditions. By using a Cole-Moore protocol we observed a significant delay in Ca(V)2.2 channel activation according to a transit of the channel through a series of closed states before channel opening. If G protein voltage-dependent modulation were carried out at these closed states, then we would have expected a greater Cole-Moore lag in the presence of a neurotransmitter. This prediction was confirmed for noradrenaline, while no change was observed in the presence of angiotensin II, a voltage-insensitive G protein modulator. We used the limiting slope method for calculation of the gating charge per channel. Effective charge z was 6.32+/-0.65 for Ca(V)2.2 channels in unregulated conditions, while GTPgammaS reduced elementary charge by approximately 4 e(0). Accordingly, increased concentration of noradrenaline induced a gradual decrease on z, indicating that this decrement was due to a G protein voltage-sensitive modulation. This paper shows for the first time a significant and reversible decrease in charge transfer of Ca(V)2.2 channels under G protein modulation, which might depend on the activated G protein inhibitory pathway.
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Kang HW, Park JY, Lee JH. Distinct contributions of different structural regions to the current kinetics of the Cav3.3 T-type Ca2+ channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:2740-8. [DOI: 10.1016/j.bbamem.2008.08.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 08/04/2008] [Accepted: 08/04/2008] [Indexed: 10/21/2022]
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Shcheglovitov A, Vitko I, Bidaud I, Baumgart JP, Navarro-Gonzalez MF, Grayson TH, Lory P, Hill CE, Perez-Reyes E. Alternative splicing within the I-II loop controls surface expression of T-type Ca(v)3.1 calcium channels. FEBS Lett 2008; 582:3765-70. [PMID: 18930057 DOI: 10.1016/j.febslet.2008.10.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Revised: 10/03/2008] [Accepted: 10/06/2008] [Indexed: 11/30/2022]
Abstract
Molecular diversity of T-type/Ca(v)3 Ca2+ channels is created by expression of three genes and alternative splicing of those genes. Prompted by the important role of the I-II linker in gating and surface expression of Ca(v)3 channels, we describe here the properties of a novel variant that partially deletes this loop. The variant is abundantly expressed in rat brain, even exceeding transcripts with the complete exon 8. Electrophysiological analysis of the Delta8b variant revealed enhanced current density compared to Ca(v)3.1a, but similar gating. Luminometry experiments revealed an increase in the expression of Delta8b channels at the plasma membrane. We conclude that alternative splicing of Ca(v)3 channels regulates surface expression and may underlie disease states in which T-channel current density is increased.
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Kurejová M, Lacinová L, Pavlovicová M, Eschbach M, Klugbauer N. The effect of the outermost basic residues in the S4 segments of the Ca(V)3.1 T-type calcium channel on channel gating. Pflugers Arch 2007; 455:527-39. [PMID: 17638012 DOI: 10.1007/s00424-007-0302-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Accepted: 05/23/2007] [Indexed: 11/26/2022]
Abstract
The contribution of voltage-sensing S4 segments in domains I to IV of the T-type Ca(V)3.1 calcium channel to channel gating was investigated by the replacement of the uppermost charged arginine residues by neutral cysteines. In each construct, either a single (R180C, R834C, R1379C or R1717C) or a double (two adjacent domains) mutation was introduced. We found that the neutralisation of the uppermost arginines in the IS4, IIS4 and IIIS4 segments shifted the voltage dependence of channel activation in a hyperpolarising direction, with the most prominent effect in the IS4 mutant. In contrast, the voltage dependence of channel inactivation was shifted towards more negative membrane potentials in all four single mutant channels, and these effects were more pronounced than the effects on channel activation. Recovery from inactivation was affected by the IS4 and IIIS4 mutations. In double mutants, the effects on channel inactivation and recovery from inactivation, but not on channel activation, were additive. Exposure of mutant channels to the reducing agent dithiothreitol did not alter channel properties. In summary, our data indicate that the S4 segments in all four domains of the Ca(V)3.1 calcium channels contribute to voltage sensing during channel inactivation, while only the S4 segments in domains I, II and III play such role in channel activation. Furthermore, the removal of the outermost basic amino acids from the IVS4 and IIIS4 and, to a lesser extent, from IS4 segments stabilised the open state of the channel, whereas neutralization from that of IIS4 destabilised it.
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Affiliation(s)
- Martina Kurejová
- Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Vlárska 5, Bratislava, Slovakia
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The effects of S4 segments on the voltage-dependence of inactivation for Cav3.1 calcium channels. CHINESE SCIENCE BULLETIN-CHINESE 2007. [DOI: 10.1007/s11434-007-0257-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Shcheglovitov A, Kostyuk P, Shuba Y. Selectivity signatures of three isoforms of recombinant T-type Ca2+ channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1406-19. [PMID: 17400181 DOI: 10.1016/j.bbamem.2007.02.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Revised: 02/16/2007] [Accepted: 02/20/2007] [Indexed: 11/27/2022]
Abstract
Voltage-gated Ca(2+) channels (VGCCs) are recognized for their superb ability for the preferred passage of Ca(2+) over any other more abundant cation present in the physiological saline. Most of our knowledge about the mechanisms of selective Ca(2+) permeation through VGCCs was derived from the studies on native and recombinant L-type representatives. However, the specifics of the selectivity and permeation of known recombinant T-type Ca(2+)-channel alpha1 subunits, Ca(v)3.1, Ca(v)3.2 and Ca(v)3.3, are still poorly defined. In the present study we provide comparative analysis of the selectivity and permeation Ca(v)3.1, Ca(v)3.2, and Ca(v)3.3 functionally expressed in Xenopus oocytes. Our data show that all Ca(v)3 channels select Ca(2+) over Na(+) by affinity. Ca(v)3.1 and Ca(v)3.2 discriminate Ca(2+), Sr(2+) and Ba(2+) based on the ion's effects on the open channel probability, whilst Ca(v)3.3 discriminates based on the ion's intrapore binding affinity. All Ca(v)3s were characterized by much smaller difference in the K(D) values for Na(+) current blockade by Ca(2+) (K(D1) approximately 6 microM) and for Ca(2+) current saturation (K(D2) approximately 2 mM) as compared to L-type channels. This enabled them to carry notable mixed Na(+)/Ca(2+) current at close to physiological Ca(2+) concentrations, which was the strongest for Ca(v)3.3, smaller for Ca(v)3.2 and the smallest for Ca(v)3.1. In addition to intrapore Ca(2+) binding site(s) Ca(v)3.2, but not Ca(v)3.1 and Ca(v)3.3, is likely to possess an extracellular Ca(2+) binding site that controls channel permeation. Our results provide novel functional tests for identifying subunits responsible for T-type Ca(2+) current in native cells.
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Affiliation(s)
- Aleksandr Shcheglovitov
- Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv-24, Ukraine
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