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Bucher ML, Dunn AR, Bradner JM, Egerton KS, Burkett JP, Johnson MA, Miller GW. Synaptic vesicle glycoprotein 2C enhances vesicular storage of dopamine and counters dopaminergic toxicity. Eur J Neurosci 2024; 59:2483-2501. [PMID: 38532289 DOI: 10.1111/ejn.16311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Revised: 02/14/2024] [Accepted: 02/22/2024] [Indexed: 03/28/2024]
Abstract
Dopaminergic neurons of the substantia nigra exist in a persistent state of vulnerability resulting from high baseline oxidative stress, high-energy demand, and broad unmyelinated axonal arborisations. Impairments in the storage of dopamine compound this stress because of cytosolic reactions that transform the vital neurotransmitter into an endogenous neurotoxicant, and this toxicity is thought to contribute to the dopamine neuron degeneration that occurs Parkinson's disease. We have previously identified synaptic vesicle glycoprotein 2C (SV2C) as a modifier of vesicular dopamine function, demonstrating that genetic ablation of SV2C in mice results in decreased dopamine content and evoked dopamine release in the striatum. Here, we adapted a previously published in vitro assay utilising false fluorescent neurotransmitter 206 (FFN206) to visualise how SV2C regulates vesicular dopamine dynamics and determined that SV2C promotes the uptake and retention of FFN206 within vesicles. In addition, we present data indicating that SV2C enhances the retention of dopamine in the vesicular compartment with radiolabelled dopamine in vesicles isolated from immortalised cells and from mouse brain. Further, we demonstrate that SV2C enhances the ability of vesicles to store the neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) and that genetic ablation of SV2C results in enhanced 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced vulnerability in mice. Together, these findings suggest that SV2C functions to enhance vesicular storage of dopamine and neurotoxicants and helps maintain the integrity of dopaminergic neurons.
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Affiliation(s)
- Meghan L Bucher
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA
| | - Amy R Dunn
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- The Jackson Laboratory, Bar Harbor, Maine, USA
| | - Joshua M Bradner
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- AbbVie CRC, Cambridge, Massachusetts, USA
| | - Kristen Stout Egerton
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- School of Education and Health Sciences, North Central College, Naperville, Illinois, USA
| | - James P Burkett
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- Department of Neurosciences, University of Toledo College of Medicine, Toledo, Ohio, USA
| | - Michelle A Johnson
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- College of Arts and Sciences, Oberlin College, Oberlin, Ohio, USA
| | - Gary W Miller
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
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Bucher ML, Dunn AR, Bradner JM, Egerton KS, Burkett JP, Johnson MA, Miller GW. Synaptic vesicle glycoprotein 2C enhances vesicular storage of dopamine and counters dopaminergic toxicity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.26.546143. [PMID: 37425736 PMCID: PMC10326994 DOI: 10.1101/2023.06.26.546143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Dopaminergic neurons of the substantia nigra exist in a persistent state of vulnerability resulting from high baseline oxidative stress, high energy demand, and broad unmyelinated axonal arborizations. Impairments in the storage of dopamine compound this stress due to cytosolic reactions that transform the vital neurotransmitter into an endogenous neurotoxicant, and this toxicity is thought to contribute to the dopamine neuron degeneration that occurs Parkinson's disease. We have previously identified synaptic vesicle glycoprotein 2C (SV2C) as a modifier of vesicular dopamine function, demonstrating that genetic ablation of SV2C in mice results in decreased dopamine content and evoked dopamine release in the striatum. Here, we adapted a previously published in vitro assay utilizing false fluorescent neurotransmitter 206 (FFN206) to visualize how SV2C regulates vesicular dopamine dynamics and determined that SV2C promotes the uptake and retention of FFN206 within vesicles. In addition, we present data indicating that SV2C enhances the retention of dopamine in the vesicular compartment with radiolabeled dopamine in vesicles isolated from immortalized cells and from mouse brain. Further, we demonstrate that SV2C enhances the ability of vesicles to store the neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) and that genetic ablation of SV2C results in enhanced 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced vulnerability in mice. Together, these findings suggest that SV2C functions to enhance vesicular storage of dopamine and neurotoxicants, and helps maintain the integrity of dopaminergic neurons.
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Affiliation(s)
- Meghan L Bucher
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
| | - Amy R Dunn
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Joshua M Bradner
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Kristen Stout Egerton
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - James P Burkett
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Michelle A Johnson
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - Gary W Miller
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY 10032, USA
- Department of Molecular Pharmacology and Therapeutics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY 10031, USA
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Bauer CS, Cohen RN, Sironi F, Livesey MR, Gillingwater TH, Highley JR, Fillingham DJ, Coldicott I, Smith EF, Gibson YB, Webster CP, Grierson AJ, Bendotti C, De Vos KJ. An interaction between synapsin and C9orf72 regulates excitatory synapses and is impaired in ALS/FTD. Acta Neuropathol 2022; 144:437-464. [PMID: 35876881 PMCID: PMC9381633 DOI: 10.1007/s00401-022-02470-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 06/17/2022] [Accepted: 07/08/2022] [Indexed: 12/16/2022]
Abstract
Dysfunction and degeneration of synapses is a common feature of amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD). A GGGGCC hexanucleotide repeat expansion in the C9ORF72 gene is the main genetic cause of ALS/FTD (C9ALS/FTD). The repeat expansion leads to reduced expression of the C9orf72 protein. How C9orf72 haploinsufficiency contributes to disease has not been resolved. Here we identify the synapsin family of synaptic vesicle proteins, the most abundant group of synaptic phosphoproteins, as novel interactors of C9orf72 at synapses and show that C9orf72 plays a cell-autonomous role in the regulation of excitatory synapses. We mapped the interaction of C9orf72 and synapsin to the N-terminal longin domain of C9orf72 and the conserved C domain of synapsin, and show interaction of the endogenous proteins in synapses. Functionally, C9orf72 deficiency reduced the number of excitatory synapses and decreased synapsin levels at remaining synapses in vitro in hippocampal neuron cultures and in vivo in the hippocampal mossy fibre system of C9orf72 knockout mice. Consistent with synaptic dysfunction, electrophysiological recordings identified impaired excitatory neurotransmission and network function in hippocampal neuron cultures with reduced C9orf72 expression, which correlated with a severe depletion of synaptic vesicles from excitatory synapses in the hippocampus of C9orf72 knockout mice. Finally, neuropathological analysis of post-mortem sections of C9ALS/FTD patient hippocampus with C9orf72 haploinsufficiency revealed a marked reduction in synapsin, indicating that disruption of the interaction between C9orf72 and synapsin may contribute to ALS/FTD pathobiology. Thus, our data show that C9orf72 plays a cell-autonomous role in the regulation of neurotransmission at excitatory synapses by interaction with synapsin and modulation of synaptic vesicle pools, and identify a novel role for C9orf72 haploinsufficiency in synaptic dysfunction in C9ALS/FTD.
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Affiliation(s)
- Claudia S Bauer
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
- Neuroscience Institute, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Rebecca N Cohen
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
- Neuroscience Institute, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Francesca Sironi
- Laboratory of Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156, Milan, Italy
| | - Matthew R Livesey
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
- Neuroscience Institute, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Thomas H Gillingwater
- Edinburgh Medical School: Biomedical Sciences, University of Edinburgh, Hugh Robson Building, Edinburgh, EH8 9XD, UK
- Euan MacDonald Centre for Motor Neuron Disease Research, Chancellor's Building, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - J Robin Highley
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
- Neuroscience Institute, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Daniel J Fillingham
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
- Neuroscience Institute, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Ian Coldicott
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
- Neuroscience Institute, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Emma F Smith
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
- Neuroscience Institute, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Yolanda B Gibson
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
- Neuroscience Institute, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Christopher P Webster
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
- Neuroscience Institute, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Andrew J Grierson
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK
- Neuroscience Institute, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Caterina Bendotti
- Laboratory of Molecular Neurobiology, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156, Milan, Italy
| | - Kurt J De Vos
- Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, 385a Glossop Road, Sheffield, S10 2HQ, UK.
- Neuroscience Institute, University of Sheffield, Western Bank, Sheffield, S10 2TN, UK.
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Synaptic vesicle glycoprotein 2C (SV2C) modulates dopamine release and is disrupted in Parkinson disease. Proc Natl Acad Sci U S A 2017; 114:E2253-E2262. [PMID: 28246328 PMCID: PMC5358362 DOI: 10.1073/pnas.1616892114] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Here we describe a role for the synaptic vesicle glycoprotein 2C (SV2C) in dopamine neurotransmission and Parkinson disease (PD). SV2C is expressed on the vesicles of dopamine-producing neurons, and genetic deletion of SV2C causes a reduction in synaptic release of dopamine. The reduced dopamine release is associated with a decrease in motor activity. SV2C is suspected of mediating the neuroprotective effects of nicotine, and we show an ablated neurochemical response to nicotine in SV2C-knockout mice. Last, we demonstrate that SV2C expression is specifically disrupted in mice that express mutated α-synuclein and in humans with PD. Together, these data establish SV2C as an important mediator of dopamine homeostasis and a potential contributor to PD pathogenesis. Members of the synaptic vesicle glycoprotein 2 (SV2) family of proteins are involved in synaptic function throughout the brain. The ubiquitously expressed SV2A has been widely implicated in epilepsy, although SV2C with its restricted basal ganglia distribution is poorly characterized. SV2C is emerging as a potentially relevant protein in Parkinson disease (PD), because it is a genetic modifier of sensitivity to l-DOPA and of nicotine neuroprotection in PD. Here we identify SV2C as a mediator of dopamine homeostasis and report that disrupted expression of SV2C within the basal ganglia is a pathological feature of PD. Genetic deletion of SV2C leads to reduced dopamine release in the dorsal striatum as measured by fast-scan cyclic voltammetry, reduced striatal dopamine content, disrupted α-synuclein expression, deficits in motor function, and alterations in neurochemical effects of nicotine. Furthermore, SV2C expression is dramatically altered in postmortem brain tissue from PD cases but not in Alzheimer disease, progressive supranuclear palsy, or multiple system atrophy. This disruption was paralleled in mice overexpressing mutated α-synuclein. These data establish SV2C as a mediator of dopamine neuron function and suggest that SV2C disruption is a unique feature of PD that likely contributes to dopaminergic dysfunction.
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Daniels V, Wood M, Leclercq K, Kaminski RM, Gillard M. Modulation of the conformational state of the SV2A protein by an allosteric mechanism as evidenced by ligand binding assays. Br J Pharmacol 2015; 169:1091-101. [PMID: 23530581 DOI: 10.1111/bph.12192] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 03/05/2013] [Accepted: 03/15/2013] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Synaptic vesicle protein 2A (SV2A) is the specific binding site of the anti-epileptic drug levetiracetam (LEV) and its higher affinity analogue UCB30889. Moreover, the protein has been well validated as a target for anticonvulsant therapy. Here, we report the identification of UCB1244283 acting as a SV2A positive allosteric modulator of UCB30889. EXPERIMENTAL APPROACH UCB1244283 was characterized in vitro using radioligand binding assays with [(3)H]UCB30889 on recombinant SV2A expressed in HEK cells and on rat cortex. In vivo, the compound was tested in sound-sensitive mice. KEY RESULTS Saturation binding experiments in the presence of UCB1244283 demonstrated a fivefold increase in the affinity of [(3)H]UCB30889 for human recombinant SV2A, combined with a twofold increase of the total number of binding sites. Similar results were obtained on rat cortex. In competition binding experiments, UCB1244283 potentiated the affinity of UCB30889 while the affinity of LEV remained unchanged. UCB1244283 significantly slowed down both the association and dissociation kinetics of [(3)H]UCB30889. Following i.c.v. administration in sound-sensitive mice, UCB1244283 showed a clear protective effect against both tonic and clonic convulsions. CONCLUSIONS AND IMPLICATIONS These results indicate that UCB1244283 can modulate the conformation of SV2A, thereby inducing a higher affinity state for UCB30889. Our results also suggest that the conformation of SV2A per se might be an important determinant of its functioning, especially during epileptic seizures. Therefore, agents that act on the conformation of SV2A might hold great potential in the search for new SV2A-based anticonvulsant therapies.
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Affiliation(s)
- V Daniels
- NewMedicines, CNS Discovery Research, UCB Pharma, Braine-l'Alleud, Belgium
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Lack of synaptic vesicle protein SV2B protects against amyloid-β25–35-induced oxidative stress, cholinergic deficit and cognitive impairment in mice. Behav Brain Res 2014; 271:277-85. [DOI: 10.1016/j.bbr.2014.06.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 06/06/2014] [Accepted: 06/08/2014] [Indexed: 11/22/2022]
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Mendoza-Torreblanca JG, Vanoye-Carlo A, Phillips-Farfán BV, Carmona-Aparicio L, Gómez-Lira G. Synaptic vesicle protein 2A: basic facts and role in synaptic function. Eur J Neurosci 2013; 38:3529-39. [DOI: 10.1111/ejn.12360] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 08/09/2013] [Accepted: 08/17/2013] [Indexed: 10/26/2022]
Affiliation(s)
| | | | | | | | - Gisela Gómez-Lira
- Department of Pharmacobiology; Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional; Calzada de los Tenorios 235 Col. Granjas Coapa C.P. 14330 D. F., Mexico
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Dardou D, Dassesse D, Cuvelier L, Deprez T, De Ryck M, Schiffmann SN. Distribution of SV2C mRNA and protein expression in the mouse brain with a particular emphasis on the basal ganglia system. Brain Res 2010; 1367:130-45. [PMID: 20869353 DOI: 10.1016/j.brainres.2010.09.063] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 09/15/2010] [Accepted: 09/15/2010] [Indexed: 10/19/2022]
Abstract
Synaptic vesicle 2 proteins (SV2), SV2A, SV2B and SV2C, are integral proteins localized on the surface of synaptic vesicles in all neurons. SV2 proteins appear to play an important, but not yet fully understood role in synaptic vesicle exocytosis and neurotransmitter release. Moreover, SV2 seems to be the receptor of the botulinum neurotoxin A. In the present study, using single and double-labeling fluorescent immunohistochemistry and in situ hybridization we have identified the brain pattern of SV2C mRNA and protein expression in mice. Our results indicated that SV2C protein was expressed in a small subset of brain regions including the olfactory bulb, olfactory tubercle, nucleus accumbens, caudate-putamen, ventral pallidum, globus pallidus, substantia nigra and the ventral tegmental area. These results were confirmed by means of in situ hybridization, except for the globus pallidus and the substantia nigra pars reticulata, in which no labeling was found, suggesting that SV2C-positive fibers in these areas are terminals of striatal projecting neurons. In the striatum, we found that, in addition to its presence in the projection neurons, SV2C was densely expressed in a fraction (around 45%) of cholinergic interneurons. In addition, our data also showed that SV2C was densely expressed in most dopaminergic neurons in the substantia nigra pars compacta and the ventral tegmental area (more than 70% of the dopaminergic neurons analyzed were SV2C-positive). Altogether, our results suggest that SV2C may contribute to the regulation of neurotransmitter release and synaptic transmission in the basal ganglia including cholinergic striatal interneurons and nigro-striatal/mesolimbic dopamine neurons.
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Affiliation(s)
- D Dardou
- Laboratory of Neurophysiology, Université Libre de Bruxelles (ULB), 808 Route de Lennik, 1070 Brussels, Belgium.
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Vautrin J. Kissing or fused since some time. Front Synaptic Neurosci 2010; 2:142. [PMID: 21423528 PMCID: PMC3059667 DOI: 10.3389/fnsyn.2010.00142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2010] [Accepted: 08/16/2010] [Indexed: 11/13/2022] Open
Affiliation(s)
- Jean Vautrin
- Max Mousseron Biomolecules Institute, Montpellier University 2 Montpellier, France
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Budzinski KL, Allen RW, Fujimoto BS, Kensel-Hammes P, Belnap DM, Bajjalieh SM, Chiu DT. Large structural change in isolated synaptic vesicles upon loading with neurotransmitter. Biophys J 2009; 97:2577-84. [PMID: 19883601 PMCID: PMC2770603 DOI: 10.1016/j.bpj.2009.08.032] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Revised: 07/27/2009] [Accepted: 08/18/2009] [Indexed: 10/20/2022] Open
Abstract
The size of a synaptic vesicle (SV) is generally thought to be determined by the amount of lipid and membrane protein it contains. Once formed, it is thought to remain constant in size. Using fluorescence correlation spectroscopy and cryogenic electron microscopy, we show that glutamatergic vesicles reversibly increase their size upon filling with glutamate. The increase ( approximately 25% in diameter) corresponds to an increase in surface area of approximately 50% and in volume of approximately 100%. This large size increase implies a large structural change in the SV upon loading with neurotransmitters. Vesicles lacking SV protein 2A (SV2A) did not manifest a change in size after loading with glutamate, indicating that SV2A is required for this phenomenon.
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Affiliation(s)
| | - Richard W. Allen
- Department of Chemistry, University of Washington, Seattle, Washington
| | | | - P. Kensel-Hammes
- Department of Pharmacology, University of Washington, Seattle, Washington
| | - David M. Belnap
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah
| | | | - Daniel T. Chiu
- Department of Chemistry, University of Washington, Seattle, Washington
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