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Mutational and Combinatorial Control of Self-Assembling and Disassembling of Human Proteasome α Subunits. Int J Mol Sci 2019; 20:ijms20092308. [PMID: 31075988 PMCID: PMC6539845 DOI: 10.3390/ijms20092308] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 05/07/2019] [Accepted: 05/07/2019] [Indexed: 12/31/2022] Open
Abstract
Eukaryotic proteasomes harbor heteroheptameric α-rings, each composed of seven different but homologous subunits α1–α7, which are correctly assembled via interactions with assembly chaperones. The human proteasome α7 subunit is reportedly spontaneously assembled into a homotetradecameric double ring, which can be disassembled into single rings via interaction with monomeric α6. We comprehensively characterized the oligomeric state of human proteasome α subunits and demonstrated that only the α7 subunit exhibits this unique, self-assembling property and that not only α6 but also α4 can disrupt the α7 double ring. We also demonstrated that mutationally monomerized α7 subunits can interact with the intrinsically monomeric α4 and α6 subunits, thereby forming heterotetradecameric complexes with a double-ring structure. The results of this study provide additional insights into the mechanisms underlying the assembly and disassembly of proteasomal subunits, thereby offering clues for the design and creation of circularly assembled hetero-oligomers based on homo-oligomeric structural frameworks.
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Structure-Function Relationship of the Voltage-Gated Calcium Channel Cav1.1 Complex. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 981:23-39. [DOI: 10.1007/978-3-319-55858-5_2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Wu J, Yan Z, Li Z, Yan C, Lu S, Dong M, Yan N. Structure of the voltage-gated calcium channel Cav1.1 complex. Science 2016; 350:aad2395. [PMID: 26680202 DOI: 10.1126/science.aad2395] [Citation(s) in RCA: 233] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The voltage-gated calcium channel Ca(v)1.1 is engaged in the excitation-contraction coupling of skeletal muscles. The Ca(v)1.1 complex consists of the pore-forming subunit α1 and auxiliary subunits α2δ, β, and γ. We report the structure of the rabbit Ca(v)1.1 complex determined by single-particle cryo-electron microscopy. The four homologous repeats of the α1 subunit are arranged clockwise in the extracellular view. The γ subunit, whose structure resembles claudins, interacts with the voltage-sensing domain of repeat IV (VSD(IV)), whereas the cytosolic β subunit is located adjacent to VSD(II) of α1. The α2 subunit interacts with the extracellular loops of repeats I to III through its VWA and Cache1 domains. The structure reveals the architecture of a prototypical eukaryotic Ca(v) channel and provides a framework for understanding the function and disease mechanisms of Ca(v) and Na(v) channels.
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Affiliation(s)
- Jianping Wu
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China. Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China. Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Zhen Yan
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China. Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China. Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Zhangqiang Li
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China. Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China. Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Chuangye Yan
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China. Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China. Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Shan Lu
- National Institute of Biological Sciences, Beijing 102206, China
| | - Mengqiu Dong
- National Institute of Biological Sciences, Beijing 102206, China
| | - Nieng Yan
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China. Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China. Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China.
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Hu H, Wang Z, Wei R, Fan G, Wang Q, Zhang K, Yin CC. The molecular architecture of dihydropyrindine receptor/L-type Ca2+ channel complex. Sci Rep 2015; 5:8370. [PMID: 25667046 PMCID: PMC4322351 DOI: 10.1038/srep08370] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 01/12/2015] [Indexed: 11/28/2022] Open
Abstract
Dihydropyridine receptor (DHPR), an L-type Ca2+ channel complex, plays an essential role in muscle contraction, secretion, integration of synaptic input in neurons and synaptic transmission. The molecular architecture of DHPR complex remains elusive. Here we present a 15-Å resolution cryo-electron microscopy structure of the skeletal DHPR/L-type Ca2+ channel complex. The DHPR has an asymmetrical main body joined by a hook-like extension. The main body is composed of a “trapezoid” and a “tetrahedroid”. Homologous crystal structure docking and site-specific antibody labelling revealed that the α1 and α2 subunits are located in the “trapezoid” and the β subunit is located in the “tetrahedroid”. This structure revealed the molecular architecture of a eukaryotic Ca2+ channel complex. Furthermore, this structure provides structural insights into the key elements of DHPR involved in physical coupling with the RyR/Ca2+ release channel and shed light onto the mechanism of excitation-contraction coupling.
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Affiliation(s)
- Hongli Hu
- Department of Biophysics, Peking University Health Science Centre, Peking University, 38 College Road, Beijing 100191, China
| | - Zhao Wang
- Department of Biophysics, Peking University Health Science Centre, Peking University, 38 College Road, Beijing 100191, China
| | - Risheng Wei
- Department of Biophysics, Peking University Health Science Centre, Peking University, 38 College Road, Beijing 100191, China
| | - Guizhen Fan
- Department of Biophysics, Peking University Health Science Centre, Peking University, 38 College Road, Beijing 100191, China
| | - Qiongling Wang
- Department of Biophysics, Peking University Health Science Centre, Peking University, 38 College Road, Beijing 100191, China
| | - Kaiming Zhang
- Department of Biophysics, Peking University Health Science Centre, Peking University, 38 College Road, Beijing 100191, China
| | - Chang-Cheng Yin
- Department of Biophysics, Peking University Health Science Centre, Peking University, 38 College Road, Beijing 100191, China
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Samsó M. 3D Structure of the Dihydropyridine Receptor of Skeletal Muscle. Eur J Transl Myol 2015; 25:4840. [PMID: 26913147 PMCID: PMC4748975 DOI: 10.4081/ejtm.2015.4840] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 12/16/2014] [Indexed: 11/22/2022] Open
Abstract
Excitation contraction coupling, the rapid and massive Ca2+ release under control of an action potential that triggers muscle contraction, takes places at specialized regions of the cell called triad junctions. There, a highly ordered supramolecular complex between the dihydropyridine receptor (DHPR) and the ryanodine receptor (RyR1) mediates the quasi-instantaneous conversion from T-tubule depolarization into Ca2+ release from the sarcoplasmic reticulum (SR). The DHPR has several key modules required for EC coupling: the voltage sensors and II-III loop in the alpha1s subunit, and the beta subunit. To gain insight into their molecular organization, this review examines the most updated 3D structure of the DHPR as obtained by transmission electron microscopy and image reconstruction. Although structure determination of a heteromeric membrane protein such as the DHPR is challenging, novel technical advances in protein expression and 3D labeling facilitated this task. The 3D structure of the DHPR complex consists of a main body with five irregular corners around its perimeter encompassing the transmembrane alpha 1s subunit besides the intracellular beta subunit, an extended extracellular alpha 2 subunit, and a bulky intracellular II-III loop. The structural definition attained at 19 Å resolution enabled docking of the atomic coordinates of structural homologs of the alpha1s and beta subunits. These structural features, together with their relative location with respect to the RyR1, are discussed in the context of the functional data.
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Affiliation(s)
- Montserrat Samsó
- Department of Physiology and Biophysics, Virginia Commonwealth University , Richmond, VA, USA
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Dayal A, Bhat V, Franzini-Armstrong C, Grabner M. Domain cooperativity in the β1a subunit is essential for dihydropyridine receptor voltage sensing in skeletal muscle. Proc Natl Acad Sci U S A 2013; 110:7488-93. [PMID: 23589859 PMCID: PMC3645543 DOI: 10.1073/pnas.1301087110] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The dihydropyridine receptor (DHPR) β1a subunit is crucial for enhancement of DHPR triad expression, assembly of DHPRs in tetrads, and elicitation of DHPRα1S charge movement--the three prerequisites of skeletal muscle excitation-contraction coupling. Despite the ability to fully target α1S into triadic junctions and tetradic arrays, the neuronal isoform β3 was unable to restore considerable charge movement (measure of α1S voltage sensing) upon expression in β1-null zebrafish relaxed myotubes, unlike the other three vertebrate β-isoforms (β1a, β2a, and β4). Thus, we used β3 for chimerization with β1a to investigate whether any of the five distinct molecular regions of β1a is dominantly involved in inducing the voltage-sensing function of α1S. Surprisingly, systematic domain swapping between β1a and β3 revealed a pivotal role of the src homology 3 (SH3) domain and C terminus of β1a in charge movement restoration. More interestingly, β1a SH3 domain and C terminus, when simultaneously engineered into β3 sequence background, were able to fully restore charge movement together with proper intracellular Ca(2+) release, suggesting cooperativity of these two domains in induction of the α1S voltage-sensing function in skeletal muscle excitation-contraction coupling. Furthermore, substitution of a proline by alanine in the putative SH3-binding polyproline motif in the proximal C terminus of β1a (also of β2a and β4) fully obstructed α1S charge movement. Consequently, we postulate a model according to which β subunits, probably via the SH3-C-terminal polyproline interaction, adapt a discrete conformation required to modify the α1S conformation apt for voltage sensing in skeletal muscle.
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Affiliation(s)
- Anamika Dayal
- Department of Medical Genetics, Molecular, and Clinical Pharmacology, Innsbruck Medical University, A-6020 Innsbruck, Austria; and
| | - Vinayakumar Bhat
- Department of Medical Genetics, Molecular, and Clinical Pharmacology, Innsbruck Medical University, A-6020 Innsbruck, Austria; and
| | - Clara Franzini-Armstrong
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104
| | - Manfred Grabner
- Department of Medical Genetics, Molecular, and Clinical Pharmacology, Innsbruck Medical University, A-6020 Innsbruck, Austria; and
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Kumoi K, Satoh T, Murata K, Hiromoto T, Mizushima T, Kamiya Y, Noda M, Uchiyama S, Yagi H, Kato K. An archaeal homolog of proteasome assembly factor functions as a proteasome activator. PLoS One 2013; 8:e60294. [PMID: 23555947 PMCID: PMC3605417 DOI: 10.1371/journal.pone.0060294] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 02/25/2013] [Indexed: 12/20/2022] Open
Abstract
Assembly of the eukaryotic 20S proteasome is an ordered process involving several proteins operating as proteasome assembly factors including PAC1-PAC2 but archaeal 20S proteasome subunits can spontaneously assemble into an active cylindrical architecture. Recent bioinformatic analysis identified archaeal PAC1-PAC2 homologs PbaA and PbaB. However, it remains unclear whether such assembly factor-like proteins play an indispensable role in orchestration of proteasome subunits in archaea. We revealed that PbaB forms a homotetramer and exerts a dual function as an ATP-independent proteasome activator and a molecular chaperone through its tentacle-like C-terminal segments. Our findings provide insights into molecular evolution relationships between proteasome activators and assembly factors.
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Affiliation(s)
- Kentaro Kumoi
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku Nagoya, Japan
| | - Tadashi Satoh
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku Nagoya, Japan
| | - Kazuyoshi Murata
- National Institute for Physiological Science, National Institutes of Natural Sciences, 5–1 Higashiyama, Myodaiji, Okazaki, Aichi, Japan
| | - Takeshi Hiromoto
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku Nagoya, Japan
| | - Tsunehiro Mizushima
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku Nagoya, Japan
- Picobiology Institute, Department of Life Science, Graduate School of Life Science, University of Hyogo, 3-2-1 Kouto, Kamigori-cho, Ako-gun, Hyogo, Japan
| | - Yukiko Kamiya
- Okazaki Institute for Integrative Bioscience and Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, Japan
| | - Masanori Noda
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, Japan
| | - Susumu Uchiyama
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, Japan
| | - Hirokazu Yagi
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku Nagoya, Japan
| | - Koichi Kato
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku Nagoya, Japan
- Okazaki Institute for Integrative Bioscience and Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, Japan
- * E-mail:
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Szpyt J, Lorenzon N, Perez CF, Norris E, Allen PD, Beam KG, Samsó M. Three-dimensional localization of the α and β subunits and of the II-III loop in the skeletal muscle L-type Ca2+ channel. J Biol Chem 2012; 287:43853-61. [PMID: 23118233 DOI: 10.1074/jbc.m112.419283] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The L-type Ca(2+) channel (dihydropyridine receptor (DHPR) in skeletal muscle acts as the voltage sensor for excitation-contraction coupling. To better resolve the spatial organization of the DHPR subunits (α(1s) or Ca(V)1.1, α(2), β(1a), δ1, and γ), we created transgenic mice expressing a recombinant β(1a) subunit with YFP and a biotin acceptor domain attached to its N- and C- termini, respectively. DHPR complexes were purified from skeletal muscle, negatively stained, imaged by electron microscopy, and subjected to single-particle image analysis. The resulting 19.1-Å resolution, three-dimensional reconstruction shows a main body of 17 × 11 × 8 nm with five corners along its perimeter. Two protrusions emerge from either face of the main body: the larger one attributed to the α(2)-δ1 subunit that forms a flexible hook-shaped feature and a smaller protrusion on the opposite side that corresponds to the II-III loop of Ca(V)1.1 as revealed by antibody labeling. Novel features discernible in the electron density accommodate the atomic coordinates of a voltage-gated sodium channel and of the β subunit in a single docking possibility that defines the α1-β interaction. The β subunit appears more closely associated to the membrane than expected, which may better account for both its role in localizing the α(1s) subunit to the membrane and its suggested role in excitation-contraction coupling.
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Affiliation(s)
- John Szpyt
- Department of Anesthesia, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA
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Minor DL, Findeisen F. Progress in the structural understanding of voltage-gated calcium channel (CaV) function and modulation. Channels (Austin) 2011; 4:459-74. [PMID: 21139419 DOI: 10.4161/chan.4.6.12867] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Voltage-gated calcium channels (CaVs) are large, transmembrane multiprotein complexes that couple membrane depolarization to cellular calcium entry. These channels are central to cardiac action potential propagation, neurotransmitter and hormone release, muscle contraction, and calcium-dependent gene transcription. Over the past six years, the advent of high-resolution structural studies of CaV components from different isoforms and CaV modulators has begun to reveal the architecture that underlies the exceptionally rich feedback modulation that controls CaV action. These descriptions of CaV molecular anatomy have provided new, structure-based insights into the mechanisms by which particular channel elements affect voltage-dependent inactivation (VDI), calcium‑dependent inactivation (CDI), and calcium‑dependent facilitation (CDF). The initial successes have been achieved through structural studies of soluble channel domains and modulator proteins and have proven most powerful when paired with biochemical and functional studies that validate ideas inspired by the structures. Here, we review the progress in this growing area and highlight some key open challenges for future efforts.
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Affiliation(s)
- Daniel L Minor
- Cardiovascular Research Institute, University of California-San Francisco, CA, USA.
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