1
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Dickwella Widanage MC, Gautam I, Sarkar D, Mentink-Vigier F, Vermaas JV, Ding SY, Lipton AS, Fontaine T, Latgé JP, Wang P, Wang T. Adaptative survival of Aspergillus fumigatus to echinocandins arises from cell wall remodeling beyond β-1,3-glucan synthesis inhibition. Nat Commun 2024; 15:6382. [PMID: 39085213 PMCID: PMC11291495 DOI: 10.1038/s41467-024-50799-8] [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: 05/13/2024] [Accepted: 07/17/2024] [Indexed: 08/02/2024] Open
Abstract
Antifungal echinocandins inhibit the biosynthesis of β-1,3-glucan, a major and essential polysaccharide component of the fungal cell wall. However, the efficacy of echinocandins against the pathogen Aspergillus fumigatus is limited. Here, we use solid-state nuclear magnetic resonance (ssNMR) and other techniques to show that echinocandins induce dynamic changes in the assembly of mobile and rigid polymers within the A. fumigatus cell wall. The reduction of β-1,3-glucan induced by echinocandins is accompanied by a concurrent increase in levels of chitin, chitosan, and highly polymorphic α-1,3-glucans, whose physical association with chitin maintains cell wall integrity and modulates water permeability. The rearrangement of the macromolecular network is dynamic and controls the permeability and circulation of the drug throughout the cell wall. Thus, our results indicate that echinocandin treatment triggers compensatory rearrangements in the cell wall that may help A. fumigatus to tolerate the drugs' antifungal effects.
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Affiliation(s)
- Malitha C Dickwella Widanage
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
- National High Magnetic Field Laboratory, Tallahassee, FL, USA
| | - Isha Gautam
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | | | | | - Josh V Vermaas
- MSU-DOE Plant Research Laboratory, East Lansing, MI, USA
- Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Shi-You Ding
- Department of Plant Biology, Michigan State University, East Lansing, MI, USA
| | - Andrew S Lipton
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Thierry Fontaine
- Institut Pasteur, Université Paris Cité, INRAE, USC2019, Unité Biologie et Pathogénicité Fongiques, F-, 75015, Paris, France
| | - Jean-Paul Latgé
- Institute of Molecular Biology and Biotechnology, University of Crete, Heraklion, Greece
| | - Ping Wang
- Departments of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Tuo Wang
- Department of Chemistry, Michigan State University, East Lansing, MI, USA.
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2
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Addison B, Bu L, Bharadwaj V, Crowley MF, Harman-Ware AE, Crowley MF, Bomble YJ, Ciesielski PN. Atomistic, macromolecular model of the Populus secondary cell wall informed by solid-state NMR. SCIENCE ADVANCES 2024; 10:eadi7965. [PMID: 38170770 PMCID: PMC10776008 DOI: 10.1126/sciadv.adi7965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 12/01/2023] [Indexed: 01/05/2024]
Abstract
Plant secondary cell walls (SCWs) are composed of a heterogeneous interplay of three major biopolymers: cellulose, hemicelluloses, and lignin. Details regarding specific intermolecular interactions and higher-order architecture of the SCW superstructure remain ambiguous. Here, we use solid-state nuclear magnetic resonance (ssNMR) measurements to infer refined details about the structural configuration, intermolecular interactions, and relative proximity of all three major biopolymers within air-dried Populus wood. To enhance the utility of these findings and enable evaluation of hypotheses in a physics-based environment in silico, the NMR observables are articulated into an atomistic, macromolecular model for biopolymer assemblies within the plant SCW. Through molecular dynamics simulation, we quantitatively evaluate several variations of atomistic models to determine structural details that are corroborated by ssNMR measurements.
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Affiliation(s)
- Bennett Addison
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA
| | - Lintao Bu
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA
| | - Vivek Bharadwaj
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA
| | - Meagan F. Crowley
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA
- Chemistry Department, Colorado School of Mines, Golden, CO, USA
| | - Anne E. Harman-Ware
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA
| | - Michael F. Crowley
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA
| | - Yannick J. Bomble
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO, USA
| | - Peter N. Ciesielski
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, USA
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3
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Gao Y, Lipton AS, Munson CR, Ma Y, Johnson KL, Murray DT, Scheller HV, Mortimer JC. Elongated galactan side chains mediate cellulose-pectin interactions in engineered Arabidopsis secondary cell walls. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023. [PMID: 37029760 DOI: 10.1111/tpj.16242] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 03/23/2023] [Accepted: 03/25/2023] [Indexed: 05/17/2023]
Abstract
The plant secondary cell wall is a thickened matrix of polysaccharides and lignin deposited at the cessation of growth in some cells. It forms the majority of carbon in lignocellulosic biomass, and it is an abundant and renewable source for forage, fiber, materials, fuels, and bioproducts. The complex structure and arrangement of the cell wall polymers mean that the carbon is difficult to access in an economical and sustainable way. One solution is to alter the cell wall polymer structure so that it is more suited to downstream processing. However, it remains difficult to predict what the effects of this engineering will be on the assembly, architecture, and properties of the cell wall. Here, we make use of Arabidopsis plants expressing a suite of genes to increase pectic galactan chain length in the secondary cell wall. Using multi-dimensional solid-state nuclear magnetic resonance, we show that increasing galactan chain length enhances pectin-cellulose spatial contacts and increases cellulose crystallinity. We also found that the increased galactan content leads to fewer spatial contacts of cellulose with xyloglucan and the backbone of pectin. Hence, we propose that the elongated galactan side chains compete with xyloglucan and the pectic backbone for cellulose interactions. Due to the galactan topology, this may result in comparatively weak interactions and disrupt the cell wall architecture. Therefore, introduction of this strategy into trees or other bioenergy crops would benefit from cell-specific expression strategies to avoid negative effects on plant growth.
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Affiliation(s)
- Yu Gao
- Joint BioEnergy Institute, Emeryville, California, 94608, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California, 94720, USA
| | - Andrew S Lipton
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington, 99354, USA
| | - Coyla R Munson
- Department of Chemistry, University of California Davis, Davis, California, 95616, USA
| | - Yingxuan Ma
- School of BioSciences, The University of Melbourne, Parkville, Victoria, 3052, Australia
- Department of Animal, Plant and Soil Sciences, La Trobe Institute for Agriculture and Food, La Trobe University, Bundoora, Victoria, 3086, Australia
| | - Kim L Johnson
- School of BioSciences, The University of Melbourne, Parkville, Victoria, 3052, Australia
- Department of Animal, Plant and Soil Sciences, La Trobe Institute for Agriculture and Food, La Trobe University, Bundoora, Victoria, 3086, Australia
| | - Dylan T Murray
- Department of Chemistry, University of California Davis, Davis, California, 95616, USA
| | - Henrik V Scheller
- Joint BioEnergy Institute, Emeryville, California, 94608, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California, 94720, USA
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, California, 94720, USA
| | - Jenny C Mortimer
- Joint BioEnergy Institute, Emeryville, California, 94608, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California, 94720, USA
- School of Agriculture, Food and Wine, Waite Research Institute, Waite Research Precinct, University of Adelaide, Glen Osmond, South Australia, 5064, Australia
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4
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Ghassemi N, Poulhazan A, Deligey F, Mentink-Vigier F, Marcotte I, Wang T. Solid-State NMR Investigations of Extracellular Matrixes and Cell Walls of Algae, Bacteria, Fungi, and Plants. Chem Rev 2021; 122:10036-10086. [PMID: 34878762 DOI: 10.1021/acs.chemrev.1c00669] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Extracellular matrixes (ECMs), such as the cell walls and biofilms, are important for supporting cell integrity and function and regulating intercellular communication. These biomaterials are also of significant interest to the production of biofuels and the development of antimicrobial treatment. Solid-state nuclear magnetic resonance (ssNMR) and magic-angle spinning-dynamic nuclear polarization (MAS-DNP) are uniquely powerful for understanding the conformational structure, dynamical characteristics, and supramolecular assemblies of carbohydrates and other biomolecules in ECMs. This review highlights the recent high-resolution investigations of intact ECMs and native cells in many organisms spanning across plants, bacteria, fungi, and algae. We spotlight the structural principles identified in ECMs, discuss the current technical limitation and underexplored biochemical topics, and point out the promising opportunities enabled by the recent advances of the rapidly evolving ssNMR technology.
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Affiliation(s)
- Nader Ghassemi
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Alexandre Poulhazan
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States.,Department of Chemistry, Université du Québec à Montréal, Montreal H2X 2J6, Canada
| | - Fabien Deligey
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | | | - Isabelle Marcotte
- Department of Chemistry, Université du Québec à Montréal, Montreal H2X 2J6, Canada
| | - Tuo Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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5
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Poulhazan A, Dickwella Widanage MC, Muszyński A, Arnold AA, Warschawski DE, Azadi P, Marcotte I, Wang T. Identification and Quantification of Glycans in Whole Cells: Architecture of Microalgal Polysaccharides Described by Solid-State Nuclear Magnetic Resonance. J Am Chem Soc 2021; 143:19374-19388. [PMID: 34735142 PMCID: PMC8630702 DOI: 10.1021/jacs.1c07429] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Indexed: 12/15/2022]
Abstract
Microalgae are photosynthetic organisms widely distributed in nature and serve as a sustainable source of bioproducts. Their carbohydrate components are also promising candidates for bioenergy production and bioremediation, but the structural characterization of these heterogeneous polymers in cells remains a formidable problem. Here we present a widely applicable protocol for identifying and quantifying the glycan content using magic-angle-spinning (MAS) solid-state NMR (ssNMR) spectroscopy, with validation from glycosyl linkage and composition analysis deduced from mass-spectrometry (MS). Two-dimensional 13C-13C correlation ssNMR spectra of a uniformly 13C-labeled green microalga Parachlorella beijerinckii reveal that starch is the most abundant polysaccharide in a naturally cellulose-deficient strain, and this polymer adopts a well-organized and highly rigid structure in the cell. Some xyloses are present in both the mobile and rigid domains of the cell wall, with their chemical shifts partially aligned with the flat-ribbon 2-fold xylan identified in plants. Surprisingly, most other carbohydrates are largely mobile, regardless of their distribution in glycolipids or cell walls. These structural insights correlate with the high digestibility of this cellulose-deficient strain, and the in-cell ssNMR methods will facilitate the investigations of other economically important algae species.
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Affiliation(s)
- Alexandre Poulhazan
- Department
of Chemistry, University of Quebec at Montreal, Montreal H2X 2J6, Canada
| | | | - Artur Muszyński
- Complex
Carbohydrate Research Center, University
of Georgia, Athens, Georgia 30602, United States
| | - Alexandre A. Arnold
- Department
of Chemistry, University of Quebec at Montreal, Montreal H2X 2J6, Canada
| | - Dror E. Warschawski
- Laboratoire
des Biomolécules, LBM, CNRS UMR 7203,
Sorbonne Université, École Normale Supérieure,
PSL University, 75005 Paris, France
| | - Parastoo Azadi
- Complex
Carbohydrate Research Center, University
of Georgia, Athens, Georgia 30602, United States
| | - Isabelle Marcotte
- Department
of Chemistry, University of Quebec at Montreal, Montreal H2X 2J6, Canada
| | - Tuo Wang
- Department
of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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6
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Chakraborty A, Fernando LD, Fang W, Dickwella Widanage MC, Wei P, Jin C, Fontaine T, Latgé JP, Wang T. A molecular vision of fungal cell wall organization by functional genomics and solid-state NMR. Nat Commun 2021; 12:6346. [PMID: 34732740 PMCID: PMC8566572 DOI: 10.1038/s41467-021-26749-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 10/21/2021] [Indexed: 12/16/2022] Open
Abstract
Vast efforts have been devoted to the development of antifungal drugs targeting the cell wall, but the supramolecular architecture of this carbohydrate-rich composite remains insufficiently understood. Here we compare the cell wall structure of a fungal pathogen Aspergillus fumigatus and four mutants depleted of major structural polysaccharides. High-resolution solid-state NMR spectroscopy of intact cells reveals a rigid core formed by chitin, β-1,3-glucan, and α-1,3-glucan, with galactosaminogalactan and galactomannan present in the mobile phase. Gene deletion reshuffles the composition and spatial organization of polysaccharides, with significant changes in their dynamics and water accessibility. The distribution of α-1,3-glucan in chemically isolated and dynamically distinct domains supports its functional diversity. Identification of valines in the alkali-insoluble carbohydrate core suggests a putative function in stabilizing macromolecular complexes. We propose a revised model of cell wall architecture which will improve our understanding of the structural response of fungal pathogens to stresses. The fungal cell wall is a complex structure composed mainly of glucans, chitin and glycoproteins. Here, the authors use solid-state NMR spectroscopy to assess the cell wall architecture of Aspergillus fumigatus, comparing wild-type cells and mutants lacking major structural polysaccharides, with insights into the distinct functions of these components.
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Affiliation(s)
- Arnab Chakraborty
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, USA
| | | | - Wenxia Fang
- State Key Laboratory of Non-food Biomass and Enzyme Technology, Guangxi Academy of Sciences, Nanning, China
| | | | - Pingzhen Wei
- State Key Laboratory of Non-food Biomass and Enzyme Technology, Guangxi Academy of Sciences, Nanning, China
| | - Cheng Jin
- State Key Laboratory of Non-food Biomass and Enzyme Technology, Guangxi Academy of Sciences, Nanning, China.,State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Thierry Fontaine
- Unité de Biologie et pathogénicité fongiques, INRAE, USC2019, Institut Pasteur, Paris, France
| | - Jean-Paul Latgé
- Institute of Molecular biology and Biotechnology (IMBBFORTH), University of Crete, Heraklion, Greece.
| | - Tuo Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, USA.
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7
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Gabrielli V, Kuraite A, da Silva MA, Edler KJ, Angulo J, Nepravishta R, Muñoz-García JC, Khimyak YZ. Spin diffusion transfer difference (SDTD) NMR: An advanced method for the characterisation of water structuration within particle networks. J Colloid Interface Sci 2021; 594:217-227. [PMID: 33756365 DOI: 10.1016/j.jcis.2021.02.094] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 02/13/2021] [Accepted: 02/23/2021] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS The classical STD NMR protocol to monitor solvent interactions in gels is strongly dependent on gelator and solvent concentrations and does not report on the degree of structuration of the solvent at the particle/solvent interface. We hypothesised that, for suspensions of large gelator particles, solvent structuration could be characterised by STD NMR when taking into account the particle-to-solvent 1H-1H spin diffusion transfer using the 1D diffusion equation. EXPERIMENTS We have carried out a systematic study on effect of gelator and solvent concentrations, and gelator surface charge, affecting the behaviour of the classical STD NMR build-up curves. To do so, we have characterised solvent interactions in dispersions of starch and cellulose-like particles prepared in deuterated water and alcohol/D2O mixtures. FINDINGS The Spin Diffusion Transfer Difference (SDTD) NMR protocol is independent of the gelator and solvent concentrations, hence allowing the estimation of the degree of solvent structuration within different particle networks. In addition, the simulation of SDTD build-up curves using the general one-dimensional diffusion equation allows the determination of minimum distances (r) and spin diffusion rates (D) at the particle/solvent interface. This novel NMR protocol can be readily extended to characterise the solvent(s) organisation in any type of colloidal systems constituted by large particles.
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Affiliation(s)
- Valeria Gabrielli
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Agne Kuraite
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | | | - Karen J Edler
- Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Jesús Angulo
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Ridvan Nepravishta
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
| | - Juan C Muñoz-García
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
| | - Yaroslav Z Khimyak
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
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8
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Kirui A, Du J, Zhao W, Barnes W, Kang X, Anderson CT, Xiao C, Wang T. A pectin methyltransferase modulates polysaccharide dynamics and interactions in Arabidopsis primary cell walls: Evidence from solid-state NMR. Carbohydr Polym 2021; 270:118370. [PMID: 34364615 DOI: 10.1016/j.carbpol.2021.118370] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/21/2021] [Accepted: 06/21/2021] [Indexed: 12/14/2022]
Abstract
Plant cell walls contain cellulose embedded in matrix polysaccharides. Understanding carbohydrate structures and interactions is critical to the production of biofuel and biomaterials using these natural resources. Here we present a solid-state NMR study of cellulose and pectin in 13C-labeled cell walls of Arabidopsis wild-type and mutant plants. Using 1D 13C and 2D 13C-13C correlation experiments, we detected a highly branched arabinan structure in qua2 and tsd2 samples, two allelic mutants for a pectin methyltransferase. Both mutants show close physical association between cellulose and the backbones of pectic homogalacturonan and rhamnogalacturonan-I. Relaxation and dipolar order parameters revealed enhanced microsecond dynamics due to polymer disorder in the mutants, but restricted motional amplitudes due to tighter pectin-cellulose associations. These molecular data shed light on polymer structure and packing in these two pectin mutants, helping to elucidate how pectin could influence cell wall architecture at the nanoscale, cell wall mechanics, and plant growth.
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Affiliation(s)
- Alex Kirui
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Juan Du
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, PR China
| | - Wancheng Zhao
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | - William Barnes
- Center for Lignocellulose Structure and Formation, The Pennsylvania State University, University Park, PA 16802, USA; Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Xue Kang
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Charles T Anderson
- Center for Lignocellulose Structure and Formation, The Pennsylvania State University, University Park, PA 16802, USA; Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Chaowen Xiao
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, PR China.
| | - Tuo Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA.
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9
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Using Solid-State 13C NMR Spectroscopy to Study the Molecular Organization of Primary Plant Cell Walls. Methods Mol Biol 2021. [PMID: 32617937 DOI: 10.1007/978-1-0716-0621-6_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
A knowledge of the mobilities of the polysaccharides or parts of polysaccharides in a cell-wall preparation provides information about possible molecular interactions among the polysaccharides in the cell wall and the relative locations of polysaccharides within the cell wall. A number of solid-state 13C NMR techniques have been developed that can be used to investigate different types of polysaccharide mobilities: rigid, semirigid, mobile, and highly mobile. In this chapter techniques are described for obtaining spectra from primary cell-wall preparations using CP/MAS, proton-rotating frame, proton spin-spin, spin-echo relaxation spectra and single-pulse excitation. We also describe how proton spin relaxation editing can be used to obtain subspectra for cell-wall polysaccharides of different mobilities, and how 2D and 3D solid-state NMR experiments have recently been applied to plant cell walls.
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10
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A grass-specific cellulose-xylan interaction dominates in sorghum secondary cell walls. Nat Commun 2020; 11:6081. [PMID: 33247125 PMCID: PMC7695714 DOI: 10.1038/s41467-020-19837-z] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 10/27/2020] [Indexed: 01/02/2023] Open
Abstract
Sorghum (Sorghum bicolor L. Moench) is a promising source of lignocellulosic biomass for the production of renewable fuels and chemicals, as well as for forage. Understanding secondary cell wall architecture is key to understanding recalcitrance i.e. identifying features which prevent the efficient conversion of complex biomass to simple carbon units. Here, we use multi-dimensional magic angle spinning solid-state NMR to characterize the sorghum secondary cell wall. We show that xylan is mainly in a three-fold screw conformation due to dense arabinosyl substitutions, with close proximity to cellulose. We also show that sorghum secondary cell walls present a high ratio of amorphous to crystalline cellulose as compared to dicots. We propose a model of sorghum cell wall architecture which is dominated by interactions between three-fold screw xylan and amorphous cellulose. This work will aid the design of low-recalcitrance biomass crops, a requirement for a sustainable bioeconomy. Sorghum is a source of lignocellulosic biomass for the production of renewable fuels. Here the authors characterise the sorghum secondary cell wall using multi-dimensional magic angle spinning solid-state NMR and present a model dominated by interactions between three-fold screw xylan and amorphous cellulose.
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11
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Addison B, Stengel D, Bharadwaj VS, Happs RM, Doeppke C, Wang T, Bomble YJ, Holland GP, Harman-Ware AE. Selective One-Dimensional 13C- 13C Spin-Diffusion Solid-State Nuclear Magnetic Resonance Methods to Probe Spatial Arrangements in Biopolymers Including Plant Cell Walls, Peptides, and Spider Silk. J Phys Chem B 2020; 124:9870-9883. [PMID: 33091304 DOI: 10.1021/acs.jpcb.0c07759] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Two-dimensional (2D) and 3D through-space 13C-13C homonuclear spin-diffusion techniques are powerful solid-state nuclear magnetic resonance (NMR) tools for extracting structural information from 13C-enriched biomolecules, but necessarily long acquisition times restrict their applications. In this work, we explore the broad utility and underutilized power of a chemical shift-selective one-dimensional (1D) version of a 2D 13C-13C spin-diffusion solid-state NMR technique. The method, which is called 1D dipolar-assisted rotational resonance (DARR) difference, is applied to a variety of biomaterials including lignocellulosic plant cell walls, microcrystalline peptide fMLF, and black widow dragline spider silk. 1D 13C-13C spin-diffusion methods described here apply in select cases in which the 1D 13C solid-state NMR spectrum displays chemical shift-resolved moieties. This is analogous to the selective 1D nuclear Overhauser effect spectroscopy (NOESY) experiment utilized in liquid-state NMR as a faster (1D instead of 2D) and often less ambiguous (direct sampling of the time domain data, coupled with increased signal averaging) alternative to 2D NOESY. Selective 1D 13C-13C spin-diffusion methods are more time-efficient than their 2D counterparts such as proton-driven spin diffusion (PDSD) and dipolar-assisted rotational resonance. The additional time gained enables measurements of 13C-13C spin-diffusion buildup curves and extraction of spin-diffusion time constants TSD, yielding detailed structural information. Specifically, selective 1D DARR difference buildup curves applied to 13C-enriched hybrid poplar woody stems confirm strong spatial interaction between lignin and acetylated xylan polymers within poplar plant secondary cell walls, and an interpolymer distance of ∼0.45-0.5 nm was estimated. Additionally, Tyr/Gly long-range correlations were observed on isotopically enriched black widow spider dragline silks.
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Affiliation(s)
- Bennett Addison
- Renewable Resources and Enabling Sciences Center, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Dillan Stengel
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182-1030, United States
| | - Vivek S Bharadwaj
- Renewable Resources and Enabling Sciences Center, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Renee M Happs
- Renewable Resources and Enabling Sciences Center, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Crissa Doeppke
- Renewable Resources and Enabling Sciences Center, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Tuo Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Yannick J Bomble
- Biosciences Center, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - Gregory P Holland
- Department of Chemistry and Biochemistry, San Diego State University, San Diego, California 92182-1030, United States
| | - Anne E Harman-Ware
- Renewable Resources and Enabling Sciences Center, 15013 Denver West Parkway, Golden, Colorado 80401, United States
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12
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Chakraborty A, Deligey F, Quach J, Mentink-Vigier F, Wang P, Wang T. Biomolecular complex viewed by dynamic nuclear polarization solid-state NMR spectroscopy. Biochem Soc Trans 2020; 48:1089-1099. [PMID: 32379300 PMCID: PMC7565284 DOI: 10.1042/bst20191084] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 01/07/2023]
Abstract
Solid-state nuclear magnetic resonance (ssNMR) is an indispensable tool for elucidating the structure and dynamics of insoluble and non-crystalline biomolecules. The recent advances in the sensitivity-enhancing technique magic-angle spinning dynamic nuclear polarization (MAS-DNP) have substantially expanded the territory of ssNMR investigations and enabled the detection of polymer interfaces in a cellular environment. This article highlights the emerging MAS-DNP approaches and their applications to the analysis of biomolecular composites and intact cells to determine the folding pathway and ligand binding of proteins, the structural polymorphism of low-populated biopolymers, as well as the physical interactions between carbohydrates, proteins, and lignin. These structural features provide an atomic-level understanding of many cellular processes, promoting the development of better biomaterials and inhibitors. It is anticipated that the capabilities of MAS-DNP in biomolecular and biomaterial research will be further enlarged by the rapid development of instrumentation and methodology.
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Affiliation(s)
- Arnab Chakraborty
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Fabien Deligey
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | - Jenny Quach
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
| | | | - Ping Wang
- Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
| | - Tuo Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA
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13
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Zhao W, Fernando LD, Kirui A, Deligey F, Wang T. Solid-state NMR of plant and fungal cell walls: A critical review. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2020; 107:101660. [PMID: 32251983 DOI: 10.1016/j.ssnmr.2020.101660] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Accepted: 03/17/2020] [Indexed: 05/22/2023]
Abstract
The cell walls of plants and microbes are a central source for bio-renewable energy and the major targets of antibiotics and antifungal agents. It is highly challenging to determine the molecular structure of complex carbohydrates, protein and lignin, and their supramolecular assembly in intact cell walls. This article selectively highlights the recent breakthroughs that employ 13C/15N solid-state NMR techniques to elucidate the architecture of fungal cell walls in Aspergillus fumigatus and the primary and secondary cell walls in a large variety of plant species such as Arabidopsis, Brachypodium, maize, and spruce. Built upon these pioneering studies, we further summarize the underexplored aspects of fungal and plant cell walls. The new research opportunities introduced by innovative methods, such as the detection of proton and quadrupolar nuclei on ultrahigh-field magnets and under fast magic-angle spinning, paramagnetic probes, natural-abundance DNP, and software development, are also critically discussed.
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Affiliation(s)
- Wancheng Zhao
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Liyanage D Fernando
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Alex Kirui
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Fabien Deligey
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Tuo Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA.
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14
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Terrett OM, Lyczakowski JJ, Yu L, Iuga D, Franks WT, Brown SP, Dupree R, Dupree P. Molecular architecture of softwood revealed by solid-state NMR. Nat Commun 2019; 10:4978. [PMID: 31673042 PMCID: PMC6823442 DOI: 10.1038/s41467-019-12979-9] [Citation(s) in RCA: 101] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Accepted: 10/10/2019] [Indexed: 11/09/2022] Open
Abstract
Economically important softwood from conifers is mainly composed of the polysaccharides cellulose, galactoglucomannan and xylan, and the phenolic polymer, lignin. The interactions between these polymers lead to wood mechanical strength and must be overcome in biorefining. Here, we use 13C multidimensional solid-state NMR to analyse the polymer interactions in never-dried cell walls of the softwood, spruce. In contrast to some earlier softwood cell wall models, most of the xylan binds to cellulose in the two-fold screw conformation. Moreover, galactoglucomannan alters its conformation by intimately binding to the surface of cellulose microfibrils in a semi-crystalline fashion. Some galactoglucomannan and xylan bind to the same cellulose microfibrils, and lignin is associated with both of these cellulose-bound polysaccharides. We propose a model of softwood molecular architecture which explains the origin of the different cellulose environments observed in the NMR experiments. Our model will assist strategies for improving wood usage in a sustainable bioeconomy.
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Affiliation(s)
- Oliver M Terrett
- Department of Biochemistry, University of Cambridge, Hopkins Building, The Downing Site, Tennis Court Road, Cambridge, CB2 1QW, UK
| | - Jan J Lyczakowski
- Department of Biochemistry, University of Cambridge, Hopkins Building, The Downing Site, Tennis Court Road, Cambridge, CB2 1QW, UK
- Natural Material Innovation Centre, University of Cambridge, 1 Scroope Terrace, Cambridge, CB2 1PX, UK
| | - Li Yu
- Department of Biochemistry, University of Cambridge, Hopkins Building, The Downing Site, Tennis Court Road, Cambridge, CB2 1QW, UK
- Natural Material Innovation Centre, University of Cambridge, 1 Scroope Terrace, Cambridge, CB2 1PX, UK
| | - Dinu Iuga
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - W Trent Franks
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - Steven P Brown
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - Ray Dupree
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK.
| | - Paul Dupree
- Department of Biochemistry, University of Cambridge, Hopkins Building, The Downing Site, Tennis Court Road, Cambridge, CB2 1QW, UK.
- Natural Material Innovation Centre, University of Cambridge, 1 Scroope Terrace, Cambridge, CB2 1PX, UK.
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15
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Kang X, Kirui A, Dickwella Widanage MC, Mentink-Vigier F, Cosgrove DJ, Wang T. Lignin-polysaccharide interactions in plant secondary cell walls revealed by solid-state NMR. Nat Commun 2019; 10:347. [PMID: 30664653 PMCID: PMC6341099 DOI: 10.1038/s41467-018-08252-0] [Citation(s) in RCA: 205] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/19/2018] [Indexed: 01/16/2023] Open
Abstract
Lignin is a complex aromatic biopolymer that strengthens and waterproofs plant secondary cell walls, enabling mechanical stability in trees and long-distance water transport in xylem. Lignin removal is a key step in paper production and biomass conversion to biofuels, motivating efforts to re-engineer lignin biosynthesis. However, the physical nature of lignin's interactions with wall polysaccharides is not well understood. Here we show that lignin self-aggregates to form highly hydrophobic and dynamically unique nanodomains, with extensive surface contacts to xylan. Solid-state NMR spectroscopy of intact maize stems, supported by dynamic nuclear polarization, reveals that lignin has abundant electrostatic interactions with the polar motifs of xylan. Lignin preferentially binds xylans with 3-fold or distorted 2-fold helical screw conformations, indicative of xylans not closely associated with cellulose. These findings advance our knowledge of the molecular-level organization of lignocellulosic biomass, providing the structural foundation for optimization of post-harvest processing for biofuels and biomaterials.
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Affiliation(s)
- Xue Kang
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Alex Kirui
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
| | | | | | - Daniel J Cosgrove
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
| | - Tuo Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA.
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16
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Kang X, Kirui A, Muszyński A, Widanage MCD, Chen A, Azadi P, Wang P, Mentink-Vigier F, Wang T. Molecular architecture of fungal cell walls revealed by solid-state NMR. Nat Commun 2018; 9:2747. [PMID: 30013106 PMCID: PMC6048167 DOI: 10.1038/s41467-018-05199-0] [Citation(s) in RCA: 162] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 06/21/2018] [Indexed: 12/12/2022] Open
Abstract
The high mortality of invasive fungal infections, and the limited number and inefficacy of antifungals necessitate the development of new agents with novel mechanisms and targets. The fungal cell wall is a promising target as it contains polysaccharides absent in humans, however, its molecular structure remains elusive. Here we report the architecture of the cell walls in the pathogenic fungus Aspergillus fumigatus. Solid-state NMR spectroscopy, assisted by dynamic nuclear polarization and glycosyl linkage analysis, reveals that chitin and α-1,3-glucan build a hydrophobic scaffold that is surrounded by a hydrated matrix of diversely linked β-glucans and capped by a dynamic layer of glycoproteins and α-1,3-glucan. The two-domain distribution of α-1,3-glucans signifies the dual functions of this molecule: contributing to cell wall rigidity and fungal virulence. This study provides a high-resolution model of fungal cell walls and serves as the basis for assessing drug response to promote the development of wall-targeted antifungals.
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Affiliation(s)
- Xue Kang
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Alex Kirui
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Artur Muszyński
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, 30602, USA
| | | | - Adrian Chen
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Parastoo Azadi
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, 30602, USA
| | - Ping Wang
- Departments of Pediatrics, and Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, USA
| | | | - Tuo Wang
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA.
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17
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Roos M, Wang T, Shcherbakov AA, Hong M. Fast Magic-Angle-Spinning 19F Spin Exchange NMR for Determining Nanometer 19F- 19F Distances in Proteins and Pharmaceutical Compounds. J Phys Chem B 2018; 122:2900-2911. [PMID: 29486126 PMCID: PMC6312665 DOI: 10.1021/acs.jpcb.8b00310] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Internuclear distances measured using NMR provide crucial constraints of three-dimensional structures but are often restricted to about 5 Å due to the weakness of nuclear-spin dipolar couplings. For studying macromolecular assemblies in biology and materials science, distance constraints beyond 1 nm will be extremely valuable. Here we present an extensive and quantitative analysis of the feasibility of 19F spin exchange NMR for precise and robust measurements of interatomic distances up to 1.6 nm at a magnetic field of 14.1 T, under 20-40 kHz magic-angle spinning (MAS). The measured distances are comparable to those achievable from paramagnetic relaxation enhancement but have higher precision, which is better than ±1 Å for short distances and ±2 Å for long distances. For 19F spins with the same isotropic chemical shift but different anisotropic chemical shifts, intermediate MAS frequencies of 15-25 kHz without 1H irradiation accelerate spin exchange. For spectrally resolved 19F-19F spin exchange, 1H-19F dipolar recoupling significantly speeds up 19F-19F spin exchange. On the basis of data from five fluorinated synthetic, pharmaceutical, and biological compounds, we obtained two general curves for spin exchange between CF groups and between CF3 and CF groups. These curves allow 19F-19F distances to be extracted from the measured spin exchange rates after taking into account 19F chemical shifts. These results demonstrate the robustness of 19F spin exchange NMR for distance measurements in a wide range of biological and chemical systems.
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Affiliation(s)
- Matthias Roos
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
| | - Tuo Wang
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
| | - Alexander A Shcherbakov
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
| | - Mei Hong
- Department of Chemistry , Massachusetts Institute of Technology , 170 Albany Street , Cambridge , Massachusetts 02139 , United States
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18
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Conformation and Trimer Association of the Transmembrane Domain of the Parainfluenza Virus Fusion Protein in Lipid Bilayers from Solid-State NMR: Insights into the Sequence Determinants of Trimer Structure and Fusion Activity. J Mol Biol 2018; 430:695-709. [PMID: 29330069 DOI: 10.1016/j.jmb.2018.01.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 12/30/2017] [Accepted: 01/02/2018] [Indexed: 01/23/2023]
Abstract
Enveloped viruses enter cells by using their fusion proteins to merge the virus lipid envelope and the cell membrane. While crystal structures of the water-soluble ectodomains of many viral fusion proteins have been determined, the structure and assembly of the C-terminal transmembrane domain (TMD) remains poorly understood. Here we use solid-state NMR to determine the backbone conformation and oligomeric structure of the TMD of the parainfluenza virus 5 fusion protein. 13C chemical shifts indicate that the central leucine-rich segment of the TMD is α-helical in POPC/cholesterol membranes and POPE membranes, while the Ile- and Val-rich termini shift to the β-strand conformation in the POPE membrane. Importantly, lipid mixing assays indicate that the TMD is more fusogenic in the POPE membrane than in the POPC/cholesterol membrane, indicating that the β-strand conformation is important for fusion by inducing membrane curvature. Incorporation of para-fluorinated Phe at three positions of the α-helical core allowed us to measure interhelical distances using 19F spin diffusion NMR. The data indicate that, at peptide:lipid molar ratios of ~1:15, the TMD forms a trimeric helical bundle with inter-helical distances of 8.2-8.4Å for L493F and L504F and 10.5Å for L500F. These data provide high-resolution evidence of trimer formation of a viral fusion protein TMD in phospholipid bilayers, and indicate that the parainfluenza virus 5 fusion protein TMD harbors two functions: the central α-helical core is the trimerization unit of the protein, while the two termini are responsible for inducing membrane curvature by transitioning to a β-sheet conformation.
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19
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Donovan KJ, Jain SK, Silvers R, Linse S, Griffin RG. Proton-Assisted Recoupling (PAR) in Peptides and Proteins. J Phys Chem B 2017; 121:10804-10817. [PMID: 29043804 PMCID: PMC8254420 DOI: 10.1021/acs.jpcb.7b08934] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Proton-assisted recoupling (PAR) is examined by exploring optimal experimental conditions and magnetization transfer rates in a variety of biologically relevant nuclear spin-systems, including simple amino acids, model peptides, and two proteins-nanocrystalline protein G (GB1), and importantly amyloid beta 1-42 (M0Aβ1-42) fibrils. A selective PAR protocol, SUBPAR (setting up better proton assisted recoupling), is described to observe magnetization transfer in one-dimensional spectra, which minimizes experiment time (in comparison to two-dimensional experiments) and thereby enables an efficient assessment of optimal PAR conditions for a desired magnetization transfer. In the case of the peptide spin systems, experimental and simulated PAR data sets are compared on a semiquantitative level, thereby elucidating the interactions influencing PAR magnetization transfer and their manifestations in different spin transfer networks. Using the optimum Rabi frequencies determined by SUBPAR, PAR magnetization transfer trajectories (or buildup curves) were recorded and compared to simulated results for short peptides. PAR buildup curves were also recorded for M0Aβ1-42 and examined conjointly with a recent structural model. The majority of salient cross-peak intensities observed in the M0Aβ1-42 PAR spectra are well-modeled with a simple biexponential equation, although the fitting parameters do not show any strong correlation to internuclear distances. Nevertheless, these parameters provide a wealth of invaluable semiquantitative structural constraints for the M0Aβ1-42. The results presented here offer a complete protocol for recording PAR 13C-13C correlation spectra with high-efficiency and using the resulting information in protein structural studies.
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Affiliation(s)
- Kevin J. Donovan
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Sheetal K. Jain
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Robert Silvers
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Sara Linse
- Department of Biochemistry and Structural Biology, Lund University, SE22100 Lund, Sweden
| | - Robert G. Griffin
- Francis Bitter Magnet Laboratory and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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20
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Xing J, Zhang S, Zhang M, Lin S. Analysis of α-helix unfolding in the pine nut peptide Lys-Cys-His-Lys-Pro induced by pulsed electric field. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2017; 97:4058-4065. [PMID: 28199023 DOI: 10.1002/jsfa.8273] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 02/07/2017] [Accepted: 02/11/2017] [Indexed: 06/06/2023]
Abstract
BACKGROUND A variety of analytical techniques were applied to explore the effects of pulsed electric field (PEF) on α-helix structural changes in the novel antioxidant peptide Lys-Cys-His-Lys-Pro (KCHKP, 611.76 Da). RESULTS The relative α-helix content of the KCHKP peptide was significantly altered from 100% to 89.91 ± 0.97% when the electric pulse frequency was 1800 Hz and the field intensity was 10 kV cm-1 . Moreover, the 1,1-diphenyl-2-pycryl-hydrazyl (DPPH) and 2,2-azinobis diammonium salt (ABTS) radical-scavenging activities of PEF-treated KCHKP were increased from 56.31% ± 0.74% to 84.33% ± 1.23% and from 40.56% ± 0.78% to 51.33% ± 0.27%, respectively. CONCLUSION PEF treatment increased peptide linkage stretch vibration and altered hydrogen bonding of KCHKP. The stability of the α-helix structure was influenced by hydrogen bonds within the peptide linkage of KCHKP induced by PEF and was related to changes in antioxidant activity. © 2017 Society of Chemical Industry.
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Affiliation(s)
- Jie Xing
- College of Food Science and Engineering, Jilin University, Changchun, PR China
| | - Sitian Zhang
- College of Food Science and Engineering, Jilin University, Changchun, PR China
| | - Mingdi Zhang
- College of Food Science and Engineering, Jilin University, Changchun, PR China
| | - Songyi Lin
- College of Food Science and Engineering, Jilin University, Changchun, PR China
- School of Food Science and Technology, Dalian Polytechnic University, Engineering Research Center of Seafood of Ministry of Education, Dalian, PR China
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21
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Phyo P, Wang T, Xiao C, Anderson CT, Hong M. Effects of Pectin Molecular Weight Changes on the Structure, Dynamics, and Polysaccharide Interactions of Primary Cell Walls of Arabidopsis thaliana: Insights from Solid-State NMR. Biomacromolecules 2017; 18:2937-2950. [DOI: 10.1021/acs.biomac.7b00888] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Pyae Phyo
- Department
of Chemistry, Massachusetts Institute of Technology, 170 Albany
Street, Cambridge, Massachusetts 02139, United States
| | - Tuo Wang
- Department
of Chemistry, Massachusetts Institute of Technology, 170 Albany
Street, Cambridge, Massachusetts 02139, United States
| | - Chaowen Xiao
- Department
of Biology, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Charles T. Anderson
- Department
of Biology, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Mei Hong
- Department
of Chemistry, Massachusetts Institute of Technology, 170 Albany
Street, Cambridge, Massachusetts 02139, United States
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22
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Wang T, Hong M. Structure and Dynamics of Polysaccharides in Plant Cell Walls from Solid-State NMR. NMR IN GLYCOSCIENCE AND GLYCOTECHNOLOGY 2017. [DOI: 10.1039/9781782623946-00290] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Multidimensional high-resolution magic-angle-spinning solid-state NMR (SSNMR) spectroscopy has recently been shown to have the unique capability of revealing the molecular structure and dynamics of insoluble macromolecules in intact plant cell walls. This chapter summarizes the 2D and 3D SSNMR techniques used so far to study cell walls and key findings about cellulose interactions with matrix polysaccharides, cellulose microfibril structure, polysaccharide–protein interactions that are responsible for wall loosening, and polysaccharide–water interactions in the hydrated primary walls. These results provide detailed molecular insights into the structure of near-native plant cell walls, and revise the conventional tethered-network model by suggesting a single-network model for the primary cell wall, which has found increasing support from recent biochemical and biomechanical data.
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Affiliation(s)
- Tuo Wang
- Department of Chemistry, Massachusetts Institute of Technology 170 Albany Street Cambridge MA 02139 USA
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology 170 Albany Street Cambridge MA 02139 USA
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23
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Qin H, Miao Y, Cross TA, Fu R. Beyond Structural Biology to Functional Biology: Solid-State NMR Experiments and Strategies for Understanding the M2 Proton Channel Conductance. J Phys Chem B 2017; 121:4799-4809. [PMID: 28425709 DOI: 10.1021/acs.jpcb.7b02468] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In terms of structural biology, solid-state NMR experiments and strategies have been well established for resonance assignments, leading to the determination of three-dimensional structures of insoluble membrane proteins in their native-like environment. It is also known that NMR has the unique capabilities to characterize structure-function relationships of membrane-bound biological systems beyond structural biology. Here, we report on solid-state NMR experiments and strategies for extracting functional activities on a sub-millisecond time scale. Specifically, we use the His37-labeled full length M2 (M2FL) protein of the Influenza A virus embedded in synthetic lipid bilayers as an example to characterize the proton conduction mechanism and kinetics. The integral membrane M2 protein assembles as a tetrameric bundle to form a proton-conducting channel that is activated by low pH and is essential for the viral lifecycle. Our results present convincing evidence for the formation of imidazolium-imidazole hydrogen bonds in the His37 tetrad at low pH and that these hydrogen bonds have a low barrier that facilitates the proton conduction mechanism in the M2FL protein. Moreover, it has been possible to measure hydronium ion exchange between water and the protons in the His37 NH bonds based on chemical exchange spectroscopy with minimized spin diffusion. The results identify an exchange rate constant of ∼4000 s-1 for pH 5.8 at -10 °C.
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Affiliation(s)
- Huajun Qin
- Department of Chemistry and Biochemistry, Florida State University , Tallahassee, Florida 32306, United States
| | - Yimin Miao
- Department of Chemistry and Biochemistry, Florida State University , Tallahassee, Florida 32306, United States
| | - Timothy A Cross
- Department of Chemistry and Biochemistry, Florida State University , Tallahassee, Florida 32306, United States.,National High Magnet Field Lab , 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Riqiang Fu
- National High Magnet Field Lab , 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
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24
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Simmons TJ, Mortimer JC, Bernardinelli OD, Pöppler AC, Brown SP, deAzevedo ER, Dupree R, Dupree P. Folding of xylan onto cellulose fibrils in plant cell walls revealed by solid-state NMR. Nat Commun 2016; 7:13902. [PMID: 28000667 PMCID: PMC5187587 DOI: 10.1038/ncomms13902] [Citation(s) in RCA: 201] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/10/2016] [Indexed: 11/25/2022] Open
Abstract
Exploitation of plant lignocellulosic biomass is hampered by our ignorance of the molecular basis for its properties such as strength and digestibility. Xylan, the most prevalent non-cellulosic polysaccharide, binds to cellulose microfibrils. The nature of this interaction remains unclear, despite its importance. Here we show that the majority of xylan, which forms a threefold helical screw in solution, flattens into a twofold helical screw ribbon to bind intimately to cellulose microfibrils in the cell wall. 13C solid-state magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, supported by in silico predictions of chemical shifts, shows both two- and threefold screw xylan conformations are present in fresh Arabidopsis stems. The twofold screw xylan is spatially close to cellulose, and has similar rigidity to the cellulose microfibrils, but reverts to the threefold screw conformation in the cellulose-deficient irx3 mutant. The discovery that induced polysaccharide conformation underlies cell wall assembly provides new principles to understand biomass properties.
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Affiliation(s)
- Thomas J. Simmons
- Department of Biochemistry and Leverhulme Centre for Natural Material Innovation, Hopkins Building, Downing Site, University of Cambridge, Cambridge CB2 1QW, UK
| | - Jenny C. Mortimer
- Department of Biochemistry and Leverhulme Centre for Natural Material Innovation, Hopkins Building, Downing Site, University of Cambridge, Cambridge CB2 1QW, UK
| | - Oigres D. Bernardinelli
- Department of Biochemistry and Leverhulme Centre for Natural Material Innovation, Hopkins Building, Downing Site, University of Cambridge, Cambridge CB2 1QW, UK
- Instituto de Física de São Carlos, Departamento de Física e Ciência Interdisciplinar, Universidade de São Paulo, Caixa Postal 369, São Carlos, Sao needs, São Paulo 13660-970, Brazil
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK
| | | | - Steven P. Brown
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK
| | - Eduardo R. deAzevedo
- Instituto de Física de São Carlos, Departamento de Física e Ciência Interdisciplinar, Universidade de São Paulo, Caixa Postal 369, São Carlos, Sao needs, São Paulo 13660-970, Brazil
| | - Ray Dupree
- Department of Physics, University of Warwick, Coventry CV4 7AL, UK
| | - Paul Dupree
- Department of Biochemistry and Leverhulme Centre for Natural Material Innovation, Hopkins Building, Downing Site, University of Cambridge, Cambridge CB2 1QW, UK
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25
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Wang T, Chen Y, Tabuchi A, Cosgrove DJ, Hong M. The Target of β-Expansin EXPB1 in Maize Cell Walls from Binding and Solid-State NMR Studies. PLANT PHYSIOLOGY 2016; 172:2107-2119. [PMID: 27729469 PMCID: PMC5129719 DOI: 10.1104/pp.16.01311] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 10/07/2016] [Indexed: 05/18/2023]
Abstract
The wall-loosening actions of β-expansins are known primarily from studies of EXPB1 extracted from maize (Zea mays) pollen. EXPB1 selectively loosens cell walls (CWs) of grasses, but its specific binding target is unknown. We characterized EXPB1 binding to sequentially extracted maize CWs, finding that the protein primarily binds glucuronoarabinoxylan (GAX), the major matrix polysaccharide in grass CWs. This binding is strongly reduced by salts, indicating that it is predominantly electrostatic in nature. For direct molecular evidence of EXPB1 binding, we conducted solid-state nuclear magnetic resonance experiments using paramagnetic relaxation enhancement (PRE), which is sensitive to distances between unpaired electrons and nuclei. By mixing 13C-enriched maize CWs with EXPB1 functionalized with a Mn2+ tag, we measured Mn2+-induced PRE Strong 1H and 13C PREs were observed for the carboxyls of GAX, followed by more moderate PREs for carboxyl groups in homogalacturonan and rhamnogalacturonan-I, indicating that EXPB1 preferentially binds GAX In contrast, no PRE was observed for cellulose, indicating very weak interaction of EXPB1 with cellulose. Dynamics experiments show that EXPB1 changes GAX mobility in a complex manner: the rigid fraction of GAX became more rigid upon EXPB1 binding while the dynamic fraction became more mobile. Combining these data with previous results, we propose that EXPB1 loosens grass CWs by disrupting noncovalent junctions between highly substituted GAX and GAX of low substitution, which binds cellulose. This study provides molecular evidence of β-expansin's target in grass CWs and demonstrates a new strategy for investigating ligand binding for proteins that are difficult to express heterologously.
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Affiliation(s)
- Tuo Wang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (T.W., M.H.); and
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 (Y.C., A.T., D.J.C.)
| | - Yuning Chen
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (T.W., M.H.); and
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 (Y.C., A.T., D.J.C.)
| | - Akira Tabuchi
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (T.W., M.H.); and
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 (Y.C., A.T., D.J.C.)
| | - Daniel J Cosgrove
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (T.W., M.H.); and
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 (Y.C., A.T., D.J.C.)
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (T.W., M.H.); and
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 (Y.C., A.T., D.J.C.)
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Yao H, Lee M, Liao SY, Hong M. Solid-State Nuclear Magnetic Resonance Investigation of the Structural Topology and Lipid Interactions of a Viral Fusion Protein Chimera Containing the Fusion Peptide and Transmembrane Domain. Biochemistry 2016; 55:6787-6800. [DOI: 10.1021/acs.biochem.6b00568] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Hongwei Yao
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Myungwoon Lee
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Shu-Yu Liao
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Wang T, Phyo P, Hong M. Multidimensional solid-state NMR spectroscopy of plant cell walls. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2016; 78:56-63. [PMID: 27552739 PMCID: PMC5244820 DOI: 10.1016/j.ssnmr.2016.08.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/09/2016] [Accepted: 08/12/2016] [Indexed: 05/18/2023]
Abstract
Plant biomass has become an important source of bio-renewable energy in modern society. The molecular structure of plant cell walls is difficult to characterize by most atomic-resolution techniques due to the insoluble and disordered nature of the cell wall. Solid-state NMR (SSNMR) spectroscopy is uniquely suited for studying native hydrated plant cell walls at the molecular level with chemical resolution. Significant progress has been made in the last five years to elucidate the molecular structures and interactions of cellulose and matrix polysaccharides in plant cell walls. These studies have focused on primary cell walls of growing plants in both the dicotyledonous and grass families, as represented by the model plants Arabidopsis thaliana, Brachypodium distachyon, and Zea mays. To date, these SSNMR results have shown that 1) cellulose, hemicellulose, and pectins form a single network in the primary cell wall; 2) in dicot cell walls, the protein expansin targets the hemicellulose-enriched region of the cellulose microfibril for its wall-loosening function; and 3) primary wall cellulose has polymorphic structures that are distinct from the microbial cellulose structures. This article summarizes these key findings, and points out future directions of investigation to advance our fundamental understanding of plant cell wall structure and function.
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Affiliation(s)
- Tuo Wang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Pyae Phyo
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
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Wang T, Yang H, Kubicki JD, Hong M. Cellulose Structural Polymorphism in Plant Primary Cell Walls Investigated by High-Field 2D Solid-State NMR Spectroscopy and Density Functional Theory Calculations. Biomacromolecules 2016; 17:2210-22. [PMID: 27192562 DOI: 10.1021/acs.biomac.6b00441] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The native cellulose of bacterial, algal, and animal origins has been well studied structurally using X-ray and neutron diffraction and solid-state NMR spectroscopy, and is known to consist of varying proportions of two allomorphs, Iα and Iβ, which differ in hydrogen bonding, chain packing, and local conformation. In comparison, cellulose structure in plant primary cell walls is much less understood because plant cellulose has lower crystallinity and extensive interactions with matrix polysaccharides. Here we have combined two-dimensional magic-angle-spinning (MAS) solid-state nuclear magnetic resonance (solid-state NMR) spectroscopy at high magnetic fields with density functional theory (DFT) calculations to obtain detailed information about the structural polymorphism and spatial distributions of plant primary-wall cellulose. 2D (13)C-(13)C correlation spectra of uniformly (13)C-labeled cell walls of several model plants resolved seven sets of cellulose chemical shifts. Among these, five sets (denoted a-e) belong to cellulose in the interior of the microfibril while two sets (f and g) can be assigned to surface cellulose. Importantly, most of the interior cellulose (13)C chemical shifts differ significantly from the (13)C chemical shifts of the Iα and Iβ allomorphs, indicating that plant primary-wall cellulose has different conformations, packing, and hydrogen bonding from celluloses of other organisms. 2D (13)C-(13)C correlation experiments with long mixing times and with water polarization transfer revealed the spatial distributions and matrix-polysaccharide interactions of these cellulose structures. Celluloses f and g are well mixed chains on the microfibril surface, celluloses a and b are interior chains that are in molecular contact with the surface chains, while cellulose c resides in the core of the microfibril, outside spin diffusion contact with the surface. Interestingly, cellulose d, whose chemical shifts differ most significantly from those of bacterial, algal, and animal cellulose, interacts with hemicellulose, is poorly hydrated, and is targeted by the protein expansin during wall loosening. To obtain information about the C6 hydroxymethyl conformation of these plant celluloses, we carried out DFT calculations of (13)C chemical shifts, using the Iα and Iβ crystal structures as templates and varying the C5-C6 torsion angle. Comparison with the experimental chemical shifts suggests that all interior cellulose favor the tg conformation, but cellulose d also has a similar propensity to adopt the gt conformation. These results indicate that cellulose in plant primary cell walls, due to their interactions with matrix polysaccharides, and has polymorphic structures that are not a simple superposition of the Iα and Iβ allomorphs, thus distinguishing them from bacterial and animal celluloses.
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Affiliation(s)
- Tuo Wang
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Hui Yang
- Department of Geosciences, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - James D Kubicki
- Department of Geological Sciences, University of Texas at El Paso , El Paso, Texas 79968, United States
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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Wang T, Hong M. Solid-state NMR investigations of cellulose structure and interactions with matrix polysaccharides in plant primary cell walls. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:503-14. [PMID: 26355148 PMCID: PMC6280985 DOI: 10.1093/jxb/erv416] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Until recently, the 3D architecture of plant cell walls was poorly understood due to the lack of high-resolution techniques for characterizing the molecular structure, dynamics, and intermolecular interactions of the wall polysaccharides in these insoluble biomolecular mixtures. We introduced multidimensional solid-state NMR (SSNMR) spectroscopy, coupled with (13)C labelling of whole plants, to determine the spatial arrangements of macromolecules in near-native plant cell walls. Here we review key evidence from 2D and 3D correlation NMR spectra that show relatively few cellulose-hemicellulose cross peaks but many cellulose-pectin cross peaks, indicating that cellulose microfibrils are not extensively coated by hemicellulose and all three major polysaccharides exist in a single network rather than two separate networks as previously proposed. The number of glucan chains in the primary-wall cellulose microfibrils has been under active debate recently. We show detailed analysis of quantitative (13)C SSNMR spectra of cellulose in various wild-type (WT) and mutant Arabidopsis and Brachypodium primary cell walls, which consistently indicate that primary-wall cellulose microfibrils contain at least 24 glucan chains.
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Affiliation(s)
- Tuo Wang
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139, USA
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Williams JK, Schmidt-Rohr K, Hong M. Aromatic spectral editing techniques for magic-angle-spinning solid-state NMR spectroscopy of uniformly (13)C-labeled proteins. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 72:118-26. [PMID: 26440131 PMCID: PMC4674322 DOI: 10.1016/j.ssnmr.2015.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/08/2015] [Accepted: 09/11/2015] [Indexed: 05/15/2023]
Abstract
The four aromatic amino acids in proteins, namely histidine, phenylalanine, tyrosine, and tryptophan, have strongly overlapping (13)C chemical shift ranges between 100 and 160ppm, and have so far been largely neglected in solid-state NMR determination of protein structures. Yet aromatic residues play important roles in biology through π-π and cation-π interactions. To better resolve and assign aromatic residues' (13)C signals in magic-angle-spinning (MAS) solid-state NMR spectra, we introduce two spectral editing techniques. The first method uses gated (1)H decoupling in a proton-driven spin-diffusion (PDSD) experiment to remove all protonated (13)C signals and retain only non-protonated carbon signals in the aromatic region of the (13)C spectra. The second technique uses chemical shift filters and (1)H-(13)C dipolar dephasing to selectively detect the Cα, Cβ and CO cross peaks of aromatic residues while suppressing the signals of all aliphatic residues. We demonstrate these two techniques on amino acids, a model peptide, and the microcrystalline protein GB1, and show that they significantly simplify the 2D NMR spectra and both reveal and permit the ready assignment of the aromatic residues' signals.
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Affiliation(s)
- Jonathan K Williams
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - Klaus Schmidt-Rohr
- Department of Chemistry, Brandeis University, Waltham, MA 02453, United States
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
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Wang T, Park YB, Cosgrove DJ, Hong M. Cellulose-Pectin Spatial Contacts Are Inherent to Never-Dried Arabidopsis Primary Cell Walls: Evidence from Solid-State Nuclear Magnetic Resonance. PLANT PHYSIOLOGY 2015; 168:871-84. [PMID: 26036615 PMCID: PMC4741345 DOI: 10.1104/pp.15.00665] [Citation(s) in RCA: 145] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 05/29/2015] [Indexed: 05/18/2023]
Abstract
The structural role of pectins in plant primary cell walls is not yet well understood because of the complex and disordered nature of the cell wall polymers. We recently introduced multidimensional solid-state nuclear magnetic resonance spectroscopy to characterize the spatial proximities of wall polysaccharides. The data showed extensive cross peaks between pectins and cellulose in the primary wall of Arabidopsis (Arabidopsis thaliana), indicating subnanometer contacts between the two polysaccharides. This result was unexpected because stable pectin-cellulose interactions are not predicted by in vitro binding assays and prevailing cell wall models. To investigate whether the spatial contacts that give rise to the cross peaks are artifacts of sample preparation, we now compare never-dried Arabidopsis primary walls with dehydrated and rehydrated samples. One-dimensional (13)C spectra, two-dimensional (13)C-(13)C correlation spectra, water-polysaccharide correlation spectra, and dynamics data all indicate that the structure, mobility, and intermolecular contacts of the polysaccharides are indistinguishable between never-dried and rehydrated walls. Moreover, a partially depectinated cell wall in which 40% of homogalacturonan is extracted retains cellulose-pectin cross peaks, indicating that the cellulose-pectin contacts are not due to molecular crowding. The cross peaks are observed both at -20 °C and at ambient temperature, thus ruling out freezing as a cause of spatial contacts. These results indicate that rhamnogalacturonan I and a portion of homogalacturonan have significant interactions with cellulose microfibrils in the native primary wall. This pectin-cellulose association may be formed during wall biosynthesis and may involve pectin entrapment in or between cellulose microfibrils, which cannot be mimicked by in vitro binding assays.
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Affiliation(s)
- Tuo Wang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (T.W., M.H.); andDepartment of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 (Y.B.P., D.J.C.)
| | - Yong Bum Park
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (T.W., M.H.); andDepartment of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 (Y.B.P., D.J.C.)
| | - Daniel J Cosgrove
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (T.W., M.H.); andDepartment of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 (Y.B.P., D.J.C.)
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (T.W., M.H.); andDepartment of Biology, Pennsylvania State University, University Park, Pennsylvania 16802 (Y.B.P., D.J.C.)
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