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Nadiminti PP, Wilson SM, van de Meene A, Hao A, Humphries J, Ratcliffe J, Yi C, Peirats-Llobet M, Lewsey MG, Whelan J, Bacic A, Doblin MS. Spatiotemporal deposition of cell wall polysaccharides in oat endosperm during grain development. PLANT PHYSIOLOGY 2023; 194:168-189. [PMID: 37862163 PMCID: PMC10756759 DOI: 10.1093/plphys/kiad566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 08/11/2023] [Accepted: 09/24/2023] [Indexed: 10/22/2023]
Abstract
Oat (Avena sativa) is a cereal crop whose grains are rich in (1,3;1,4)-β-D-glucan (mixed-linkage glucan or MLG), a soluble dietary fiber. In our study, we analyzed oat endosperm development in 2 Canadian varieties with differing MLG content and nutritional value. We confirmed that oat undergoes a nuclear type of endosperm development but with a shorter cellularization phase than barley (Hordeum vulgare). Callose and cellulose were the first polysaccharides to be detected in the early anticlinal cell walls at 11 days postemergence (DPE) of the panicle. Other polysaccharides such as heteromannan and homogalacturonan were deposited early in cellularization around 12 DPE after the first periclinal walls are laid down. In contrast to barley, heteroxylan deposition coincided with completion of cellularization and was detected from 14 DPE but was only detectable after demasking. Notably, MLG was the last polysaccharide to be laid down at 18 DPE within the differentiation phase, rather than during cellularization. In addition, differences in the spatiotemporal patterning of MLG were also observed between the 2 varieties. The lower MLG-containing cultivar AC Morgan (3.5% w/w groats) was marked by the presence of a discontinuous pattern of MLG labeling, while labeling in the same walls in CDC Morrison (5.6% w/w groats) was mostly even and continuous. RNA-sequencing analysis revealed higher transcript levels of multiple MLG biosynthetic cellulose synthase-like F (CSLF) and CSLH genes during grain development in CDC Morrison compared with AC Morgan that likely contributes to the increased abundance of MLG at maturity in CDC Morrison. CDC Morrison was also observed to have smaller endosperm cells with thicker walls than AC Morgan from cellularization onwards, suggesting the processes controlling cell size and shape are established early in development. This study has highlighted that the molecular processes influencing MLG content and deposition are more complex than previously imagined.
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Affiliation(s)
- Pavani P Nadiminti
- La Trobe Institute for Sustainable Agriculture & Food, Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria 3086, Australia
| | - Sarah M Wilson
- La Trobe Institute for Sustainable Agriculture & Food, Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria 3086, Australia
| | - Allison van de Meene
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Alfie Hao
- La Trobe Institute for Sustainable Agriculture & Food, Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria 3086, Australia
| | - John Humphries
- La Trobe Institute for Sustainable Agriculture & Food, Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria 3086, Australia
| | - Julian Ratcliffe
- Latrobe University Bioimaging Platform, La Trobe University, Bundoora, Victoria 3086, Australia
| | - Changyu Yi
- La Trobe Institute for Sustainable Agriculture & Food, Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria 3086, Australia
| | - Marta Peirats-Llobet
- La Trobe Institute for Sustainable Agriculture & Food, Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria 3086, Australia
| | - Mathew G Lewsey
- La Trobe Institute for Sustainable Agriculture & Food, Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria 3086, Australia
| | - James Whelan
- La Trobe Institute for Sustainable Agriculture & Food, Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria 3086, Australia
| | - Antony Bacic
- La Trobe Institute for Sustainable Agriculture & Food, Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria 3086, Australia
| | - Monika S Doblin
- La Trobe Institute for Sustainable Agriculture & Food, Department of Animal, Plant and Soil Sciences, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria 3086, Australia
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2
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Morais MAB, Paiva JH, Murakami MT. Molecular plasticity of CBM3 ancillary domain leads to conformational changes in the cellulose binding interface. Biochem Biophys Res Commun 2023; 645:71-78. [PMID: 36680939 DOI: 10.1016/j.bbrc.2023.01.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 12/14/2022] [Accepted: 01/10/2023] [Indexed: 01/12/2023]
Abstract
Carbohydrate-binding modules (CBMs) constitute independently folded domains typically associated with carbohydrate-active enzymes (CAZymes). These modules are considered to have a rigid structure without notable conformational changes upon ligand binding, exhibiting a complementary topography in relation to the target carbohydrate. Herein, the high-resolution SAD-solved structure of a CBM from family 3 (BsCBM3) that binds to crystalline cellulose is reported in two crystalline forms. This module showed molecular plasticity with structural differences detected between the two crystalline forms and high RMSD values when compared to NMR ensemble of models. Pronounced structural variances were observed in the cellulose binding interface between NMR and XTAL structures, which were corroborated by molecular dynamics simulations. These findings support that family 3 CBMs targeting to cellulose are rather structurally dynamic modules than rigid entities, suggesting a potential role of conformational changes in polysaccharide recognition and modulation of enzyme activity.
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Affiliation(s)
- Mariana Abrahão Bueno Morais
- Brazilian Biorenewables National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, SP, Brazil
| | - Joice Helena Paiva
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, SP, Brazil
| | - Mário Tyago Murakami
- Brazilian Biorenewables National Laboratory, Brazilian Center for Research in Energy and Materials, Campinas, SP, Brazil.
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3
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Zhang Y, Yin Q, Qin W, Gao H, Du J, Chen J, Li H, Zhou G, Wu H, Wu AM. The Class II KNOX family members KNAT3 and KNAT7 redundantly participate in Arabidopsis seed coat mucilage biosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:3477-3495. [PMID: 35188965 DOI: 10.1093/jxb/erac066] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 02/18/2022] [Indexed: 06/14/2023]
Abstract
The production of Arabidopsis seed mucilage involves complex polysaccharide biosynthetic pathways and developmental processes in seed epidermal cells. Although the polysaccharide components of Arabidopsis seed mucilage have been identified, their regulatory mechanism requires further investigation. Here, we show that Class II KNOX gene family members KNAT3 and KNAT7 play an essential role in regulating mucilage production in the early developmental stages of Arabidopsis seeds. Double mutant knat3knat7 resulted in defective seed mucilage production and columellae formation, whereas knat3 showed a normal phenotype compared with wild type, and the mucilage thickness in knat7 was slightly disturbed. Rhamnogalacturonan I (RG-I) and its biosynthetic substrates galacturonic acid and rhamnose were reduced in both the adherent and soluble mucilage of knat3knat7. Comparative transcriptome analysis on whole seeds suggested that polysaccharide, glucosinolate and anthocyanin biosynthetic pathways were specifically repressed in knat3knat7. Transient co-expression of KNAT3 and KNAT7 with promoter regions of candidate genes in Arabidopsis protoplasts revealed that both KNAT3 and KNAT7 act as positive regulators of the RG-I biosynthetic gene MUCILAGE-MODIFIED 4 (MUM4, AT1G53500). Collectively, our results demonstrate that KNAT3 and KNAT7 are multifunctional transcription factors in secondary cell wall development and redundantly modulate mucilage biosynthesis in Arabidopsis seeds.
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Affiliation(s)
- Yuanyuan Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University. Guangzhou, 510642, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architectures, South China Agricultural University. Guangzhou, 510642, China
| | - Qi Yin
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University. Guangzhou, 510642, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architectures, South China Agricultural University. Guangzhou, 510642, China
| | - Wenqi Qin
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University. Guangzhou, 510642, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architectures, South China Agricultural University. Guangzhou, 510642, China
| | - Han Gao
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University. Guangzhou, 510642, China
- College of life sciences, South China Agricultural University. Guangzhou, 510642, China
| | - Jinge Du
- Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China
| | - Jiajun Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University. Guangzhou, 510642, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architectures, South China Agricultural University. Guangzhou, 510642, China
| | - Huiling Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University. Guangzhou, 510642, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architectures, South China Agricultural University. Guangzhou, 510642, China
| | - Gongke Zhou
- College of Resource and Environment, Qingdao Agricultural University, Qingdao, 266109, China
| | - Hong Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University. Guangzhou, 510642, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architectures, South China Agricultural University. Guangzhou, 510642, China
- College of life sciences, South China Agricultural University. Guangzhou, 510642, China
| | - Ai-Min Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University. Guangzhou, 510642, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architectures, South China Agricultural University. Guangzhou, 510642, China
- Guangdong Laboratory of Lingnan Modern Agriculture, Guangzhou 510642, China
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4
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Salmeán AA, Willats WGT, Ribeiro S, Andersen TJ, Ellegaard M. Over 100-Year Preservation and Temporal Fluctuations of Cell Wall Polysaccharides in Marine Sediments. FRONTIERS IN PLANT SCIENCE 2022; 13:785902. [PMID: 35519816 PMCID: PMC9062592 DOI: 10.3389/fpls.2022.785902] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 02/28/2022] [Indexed: 05/16/2023]
Abstract
Polysaccharides constitute an important carbon pool in marine systems, but much is still unknown about the fate and degradation of these compounds. They are derived partly from production in situ, and in coastal areas, they are partly terrestrially derived, originating from freshwater runoff from land. The aim of this study was to test the applicability of high-throughput polysaccharide profiling for plant and algal cell-wall compounds in dated sediment cores from a coastal marine environment, to examine the preservation of cell-wall polysaccharides and explore their potential as proxies for temporal environmental changes. Preserved compounds and remains of organisms are routinely used as paleoenvironmental proxies as the amount and composition of different compounds that can provide insight into past environmental conditions, and novel means for reporting environmental changes are highly sought.
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Affiliation(s)
- Armando A. Salmeán
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
- Department of Technology, University College Copenhagen, Copenhagen, Denmark
| | - William George Tycho Willats
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Sofia Ribeiro
- Geological Survey of Denmark and Greenland, Copenhagen, Denmark
| | - Thorbjørn Joest Andersen
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Marianne Ellegaard
- Department of Technology, University College Copenhagen, Copenhagen, Denmark
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5
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Pelus A, Bordes G, Barbe S, Bouchiba Y, Burnard C, Cortés J, Enjalbert B, Esque J, Estaña A, Fauré R, Henras AK, Heux S, Le Men C, Millard P, Nouaille S, Pérochon J, Toanen M, Truan G, Verdier A, Wagner C, Romeo Y, Montanier CY. A tripartite carbohydrate-binding module to functionalize cellulose nanocrystals. Biomater Sci 2021; 9:7444-7455. [PMID: 34647546 DOI: 10.1039/d1bm01156a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The development of protein and microorganism engineering have led to rising expectations of biotechnology in the design of emerging biomaterials, putatively of high interest to reduce our dependence on fossil carbon resources. In this way, cellulose, a renewable carbon based polysaccharide and derived products, displays unique properties used in many industrial applications. Although the functionalization of cellulose is common, it is however limited in terms of number and type of functions. In this work, a Carbohydrate-Binding Module (CBM) was used as a central core to provide a versatile strategy to bring a large diversity of functions to cellulose surfaces. CBM3a from Clostridium thermocellum, which has a high affinity for crystalline cellulose, was flanked through linkers with a streptavidin domain and an azide group introduced through a non-canonical amino acid. Each of these two extra domains was effectively produced and functionalized with a variety of biological and chemical molecules. Structural properties of the resulting tripartite chimeric protein were investigated using molecular modelling approaches, and its potential for the multi-functionalization of cellulose was confirmed experimentally. As a proof of concept, we show that cellulose can be labelled with a fluorescent version of the tripartite protein grafted to magnetic beads and captured using a magnet.
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Affiliation(s)
- Angeline Pelus
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Gaëlle Bordes
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Integrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France.
| | - Sophie Barbe
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Younes Bouchiba
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Callum Burnard
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Juan Cortés
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, France
| | - Brice Enjalbert
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Jeremy Esque
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | | | - Régis Fauré
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Anthony K Henras
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Integrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France.
| | - Stéphanie Heux
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Claude Le Men
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Pierre Millard
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | | | - Julien Pérochon
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Marion Toanen
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Gilles Truan
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Amandine Verdier
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Camille Wagner
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France.
| | - Yves Romeo
- Molecular, Cellular and Developmental biology department (MCD), Centre de Biologie Integrative (CBI), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France.
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6
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Głazowska S, Mravec J. An aptamer highly specific to cellulose enables the analysis of the association of cellulose with matrix cell wall polymers in vitro and in muro. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 108:579-599. [PMID: 34314513 DOI: 10.1111/tpj.15442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 06/27/2021] [Accepted: 07/20/2021] [Indexed: 06/13/2023]
Abstract
The current toolbox of cell wall-directed molecular probes has been pivotal for advancing basic and application-oriented plant carbohydrate research; however, it still exhibits limitations regarding target diversity and specificity. Scarcity of probes targeting intramolecular associations between cell wall polymers particularly hinders our understanding of the cell wall microstructure and affects the development of effective means for its efficient deconstruction for bioconversion. Here we report a detailed characterization of a cellulose-binding DNA aptamer CELAPT MINI using a combination of various in vitro biochemical, biophysical, and molecular biology techniques. Our results show evidence for its high specificity towards long non-substituted β-(1-4)-glucan chains in both crystalline and amorphous forms. Fluorescent conjugates of CELAPT MINI are applicable as in situ cellulose probes and are well suited for various microscopy techniques, including super-resolution imaging. Compatibility of fluorescent CELAPT MINI variants with immunodetection of cell wall matrix polymers enabled them simultaneously to resolve the fibrillar organization of complex cellulose-enriched pulp material and to quantify the level of cellulose masking by xyloglucan and xylan. Using enzymatically, chemically, or genetically modulated Brachypodium internode sections we showed the diversity in cell wall packing among various cell types and even cell wall microdomains. We showed that xylan is the most prominent, but not the only, cellulose-masking agent in Brachypodium internode tissues. These results collectively highlight the hitherto unexplored potential to expand the cell wall probing toolbox with highly specific and versatile in vitro generated polynucleotide probes.
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Affiliation(s)
- Sylwia Głazowska
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg, DK-1871, Denmark
| | - Jozef Mravec
- Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg, DK-1871, Denmark
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7
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Liu J, Sun D, Zhu J, Liu C, Liu W. Carbohydrate-binding modules targeting branched polysaccharides: overcoming side-chain recalcitrance in a non-catalytic approach. BIORESOUR BIOPROCESS 2021; 8:28. [PMID: 38650221 PMCID: PMC10992016 DOI: 10.1186/s40643-021-00381-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 04/07/2021] [Indexed: 12/25/2022] Open
Abstract
Extensive decoration of backbones is a major factor resulting in resistance of enzymatic conversion in hemicellulose and other branched polysaccharides. Employing debranching enzymes is the main strategy to overcome this kind of recalcitrance at present. A carbohydrate-binding module (CBM) is a contiguous amino acid sequence that can promote the binding of enzymes to various carbohydrates, thereby facilitating enzymatic hydrolysis. According to previous studies, CBMs can be classified into four types based on their preference in ligand type, where Type III and IV CBMs prefer to branched polysaccharides than the linear and thus are able to specifically enhance the hydrolysis of substrates containing side chains. With a role in dominating the hydrolysis of branched substrates, Type III and IV CBMs could represent a non-catalytic approach in overcoming side-chain recalcitrance.
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Affiliation(s)
- Jiawen Liu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China
| | - Di Sun
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China
| | - Jingrong Zhu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China
| | - Cong Liu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China.
| | - Weijie Liu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China.
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8
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DeVree BT, Steiner LM, Głazowska S, Ruhnow F, Herburger K, Persson S, Mravec J. Current and future advances in fluorescence-based visualization of plant cell wall components and cell wall biosynthetic machineries. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:78. [PMID: 33781321 PMCID: PMC8008654 DOI: 10.1186/s13068-021-01922-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 03/05/2021] [Indexed: 05/18/2023]
Abstract
Plant cell wall-derived biomass serves as a renewable source of energy and materials with increasing importance. The cell walls are biomacromolecular assemblies defined by a fine arrangement of different classes of polysaccharides, proteoglycans, and aromatic polymers and are one of the most complex structures in Nature. One of the most challenging tasks of cell biology and biomass biotechnology research is to image the structure and organization of this complex matrix, as well as to visualize the compartmentalized, multiplayer biosynthetic machineries that build the elaborate cell wall architecture. Better knowledge of the plant cells, cell walls, and whole tissue is essential for bioengineering efforts and for designing efficient strategies of industrial deconstruction of the cell wall-derived biomass and its saccharification. Cell wall-directed molecular probes and analysis by light microscopy, which is capable of imaging with a high level of specificity, little sample processing, and often in real time, are important tools to understand cell wall assemblies. This review provides a comprehensive overview about the possibilities for fluorescence label-based imaging techniques and a variety of probing methods, discussing both well-established and emerging tools. Examples of applications of these tools are provided. We also list and discuss the advantages and limitations of the methods. Specifically, we elaborate on what are the most important considerations when applying a particular technique for plants, the potential for future development, and how the plant cell wall field might be inspired by advances in the biomedical and general cell biology fields.
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Affiliation(s)
- Brian T DeVree
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
| | - Lisa M Steiner
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
| | - Sylwia Głazowska
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
| | - Felix Ruhnow
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
| | - Klaus Herburger
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
| | - Staffan Persson
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
- Joint International Research Laboratory of Metabolic and Developmental Sciences, State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Jozef Mravec
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark
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9
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New Family of Carbohydrate-Binding Modules Defined by a Galactosyl-Binding Protein Module from a Cellvibrio japonicus Endo-Xyloglucanase. Appl Environ Microbiol 2021; 87:e0263420. [PMID: 33355108 DOI: 10.1128/aem.02634-20] [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] [Indexed: 02/04/2023] Open
Abstract
Carbohydrate-binding modules (CBMs) are usually appended to carbohydrate-active enzymes (CAZymes) and serve to potentiate catalytic activity, for example, by increasing substrate affinity. The Gram-negative soil saprophyte Cellvibrio japonicus is a valuable source for CAZyme and CBM discovery and characterization due to its innate ability to degrade a wide array of plant polysaccharides. Bioinformatic analysis of the CJA_2959 gene product from C. japonicus revealed a modular architecture consisting of a fibronectin type III (Fn3) module, a cryptic module of unknown function (X181), and a glycoside hydrolase family 5 subfamily 4 (GH5_4) catalytic module. We previously demonstrated that the last of these, CjGH5F, is an efficient and specific endo-xyloglucanase (M. A. Attia, C. E. Nelson, W. A. Offen, N. Jain, et al., Biotechnol Biofuels 11:45, 2018, https://doi.org/10.1186/s13068-018-1039-6). In the present study, C-terminal fusion of superfolder green fluorescent protein in tandem with the Fn3-X181 modules enabled recombinant production and purification from Escherichia coli. Native affinity gel electrophoresis revealed binding specificity for the terminal galactose-containing plant polysaccharides galactoxyloglucan and galactomannan. Isothermal titration calorimetry further evidenced a preference for galactoxyloglucan polysaccharide over short oligosaccharides comprising the limit-digest products of CjGH5F. Thus, our results identify the X181 module as the defining member of a new CBM family, CBM88. In addition to directly revealing the function of this CBM in the context of xyloglucan metabolism by C. japonicus, this study will guide future bioinformatic and functional analyses across microbial (meta)genomes. IMPORTANCE This study reveals carbohydrate-binding module family 88 (CBM88) as a new family of galactose-binding protein modules, which are found in series with diverse microbial glycoside hydrolases, polysaccharide lyases, and carbohydrate esterases. The definition of CBM88 in the carbohydrate-active enzymes classification (http://www.cazy.org/CBM88.html) will significantly enable future microbial (meta)genome analysis and functional studies.
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10
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van de Meene A, McAloney L, Wilson SM, Zhou J, Zeng W, McMillan P, Bacic A, Doblin MS. Interactions between Cellulose and (1,3;1,4)-β-glucans and Arabinoxylans in the Regenerating Wall of Suspension Culture Cells of the Ryegrass Lolium multiflorum. Cells 2021; 10:cells10010127. [PMID: 33440743 PMCID: PMC7828102 DOI: 10.3390/cells10010127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/04/2021] [Accepted: 01/06/2021] [Indexed: 12/11/2022] Open
Abstract
Plant cell walls (PCWs) form the outer barrier of cells that give the plant strength and directly interact with the environment and other cells in the plant. PCWs are composed of several polysaccharides, of which cellulose forms the main fibrillar network. Enmeshed between these fibrils of cellulose are non-cellulosic polysaccharides (NCPs), pectins, and proteins. This study investigates the sequence, timing, patterning, and architecture of cell wall polysaccharide regeneration in suspension culture cells (SCC) of the grass species Lolium multiflorum (Lolium). Confocal, superresolution, and electron microscopies were used in combination with cytochemical labeling to investigate polysaccharide deposition in SCC after protoplasting. Cellulose was the first polysaccharide observed, followed shortly thereafter by (1,3;1,4)-β-glucan, which is also known as mixed-linkage glucan (MLG), arabinoxylan (AX), and callose. Cellulose formed fibrils with AX and produced a filamentous-like network, whereas MLG formed punctate patches. Using colocalization analysis, cellulose and AX were shown to interact during early stages of wall generation, but this interaction reduced over time as the wall matured. AX and MLG interactions increased slightly over time, but cellulose and MLG were not seen to interact. Callose initially formed patches that were randomly positioned on the protoplast surface. There was no consistency in size or location over time. The architecture observed via superresolution microscopy showed similarities to the biophysical maps produced using atomic force microscopy and can give insight into the role of polysaccharides in PCWs.
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Affiliation(s)
- Allison van de Meene
- ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia; (A.v.d.M.); (L.M.); (S.M.W.); (J.Z.); (W.Z.); (A.B.)
| | - Lauren McAloney
- ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia; (A.v.d.M.); (L.M.); (S.M.W.); (J.Z.); (W.Z.); (A.B.)
| | - Sarah M. Wilson
- ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia; (A.v.d.M.); (L.M.); (S.M.W.); (J.Z.); (W.Z.); (A.B.)
| | - JiZhi Zhou
- ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia; (A.v.d.M.); (L.M.); (S.M.W.); (J.Z.); (W.Z.); (A.B.)
| | - Wei Zeng
- ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia; (A.v.d.M.); (L.M.); (S.M.W.); (J.Z.); (W.Z.); (A.B.)
- Sino-Australia Plant Wall Research Centre, State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Lin’an 311300, China
| | - Paul McMillan
- Biological Optical Microscopy Platform, The University of Melbourne, Melbourne, VIC 3010, Australia;
- Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia
| | - Antony Bacic
- ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia; (A.v.d.M.); (L.M.); (S.M.W.); (J.Z.); (W.Z.); (A.B.)
- Sino-Australia Plant Wall Research Centre, State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Lin’an 311300, China
- Department of Animal, Plant & Soil Sciences, Latrobe Institute for Agriculture & Food (LIAF), Latrobe University, Melbourne, VIC 3086, Australia
| | - Monika S. Doblin
- ARC Centre of Excellence in Plant Cell Walls, School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia; (A.v.d.M.); (L.M.); (S.M.W.); (J.Z.); (W.Z.); (A.B.)
- Sino-Australia Plant Wall Research Centre, State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Lin’an 311300, China
- Department of Animal, Plant & Soil Sciences, Latrobe Institute for Agriculture & Food (LIAF), Latrobe University, Melbourne, VIC 3086, Australia
- Correspondence:
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11
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Peaucelle A, Wightman R, Haas KT. Multicolor 3D-dSTORM Reveals Native-State Ultrastructure of Polysaccharides' Network during Plant Cell Wall Assembly. iScience 2020; 23:101862. [PMID: 33336161 PMCID: PMC7733027 DOI: 10.1016/j.isci.2020.101862] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/07/2020] [Accepted: 11/20/2020] [Indexed: 12/17/2022] Open
Abstract
The plant cell wall, a form of the extracellular matrix, is a complex and dynamic network of polymers mediating a plethora of physiological functions. How polysaccharides assemble into a coherent and heterogeneous matrix remains mostly undefined. Further progress requires improved molecular-level visualization methods that would gain a deeper understanding of the cell wall nanoarchitecture. dSTORM, a type of super-resolution microscopy, permits quantitative nanoimaging of the cell wall. However, due to the lack of single-cell model systems and the requirement of tissue-level imaging, its use in plant science is almost absent. Here we overcome these limitations; we compare two methods to achieve three-dimensional dSTORM and identify optimal photoswitching dyes for tissue-level multicolor nanoscopy. Combining dSTORM with spatial statistics, we reveal and characterize the ultrastructure of three major polysaccharides, callose, mannan, and cellulose, in the plant cell wall precursor and provide evidence for cellulose structural re-organization related to callose content.
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Affiliation(s)
- Alexis Peaucelle
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000, Versailles, France
| | - Raymond Wightman
- Microscopy Core Facility, Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge, CB2 1LR, UK
| | - Kalina Tamara Haas
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000, Versailles, France
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12
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Haas KT, Rivière M, Wightman R, Peaucelle A. Multitarget Immunohistochemistry for Confocal and Super-resolution Imaging of Plant Cell Wall Polysaccharides. Bio Protoc 2020; 10:e3783. [PMID: 33659438 PMCID: PMC7842508 DOI: 10.21769/bioprotoc.3783] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/21/2020] [Accepted: 08/17/2020] [Indexed: 11/02/2022] Open
Abstract
The plant cell wall (PCW) is a pecto-cellulosic extracellular matrix that envelopes the plant cell. By integrating extra-and intra-cellular cues, PCW mediates a plethora of essential physiological functions. Notably, it permits controlled and oriented tissue growth by tuning its local mechano-chemical properties. To refine our knowledge of these essential properties of PCW, we need an appropriate tool for the accurate observation of the native (in muro) structure of the cell wall components. The label-free techniques, such as AFM, EM, FTIR, and Raman microscopy, are used; however, they either do not have the chemical or spatial resolution. Immunolabeling with electron microscopy allows observation of the cell wall nanostructure, however, it is mostly limited to single and, less frequently, multiple labeling. Immunohistochemistry (IHC) is a versatile tool to analyze the distribution and localization of multiple biomolecules in the tissue. The subcellular resolution of chemical changes in the cell wall component can be observed with standard diffraction-limited optical microscopy. Furthermore, novel chemical imaging tools such as multicolor 3D dSTORM (Three-dimensional, direct Stochastic Optical Reconstruction Microscopy) nanoscopy makes it possible to resolve the native structure of the cell wall polymers with nanometer precision and in three dimensions. Here we present a protocol for preparing multi-target immunostaining of the PCW components taking as example Arabidopsis thaliana, Star fruit (Averrhoa carambola), and Maize thin tissue sections. This protocol is compatible with the standard confocal microscope, dSTORM nanoscope, and can also be implemented for other optical nanoscopy such as STED (Stimulated Emission Depletion Microscopy). The protocol can be adapted for any other subcellular compartments, plasma membrane, cytoplasmic, and intracellular organelles.
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Affiliation(s)
- Kalina T. Haas
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000, Versailles, France
| | - Methieu Rivière
- Faculty of Life Sciences, School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 69978, Israel
| | - Raymond Wightman
- Microscopy Core Facility, Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge, CB2 1LR, UK
| | - Alexis Peaucelle
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000, Versailles, France
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13
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Shi Z, Han C, Zhang X, Tian L, Wang L. Novel Synergistic Mechanism for Lignocellulose Degradation by a Thermophilic Filamentous Fungus and a Thermophilic Actinobacterium Based on Functional Proteomics. Front Microbiol 2020; 11:539438. [PMID: 33042052 PMCID: PMC7518101 DOI: 10.3389/fmicb.2020.539438] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 08/24/2020] [Indexed: 11/13/2022] Open
Abstract
Effective artificial microbial consortia containing microorganisms with desired biological functions have the potential to optimize the lignocellulose-based bioindustry. Thermobifida fusca was a dominant actinobacterium in high-temperature corn stalk composts, but it was unable to grow alone in corn stalk solid medium. Interestingly, T. fusca showed good growth and secreted enzymes when cocultured with Thermomyces lanuginosus. T. lanuginosus grew firstly during the initial stage, whereas T. fusca dominated the system subsequently during cocultivation. The secretome indicated that T. lanuginosus mainly degraded xylan by expressing a GH11 xylanase (g4601.t1, GenBank AAB94633.1; with relative secretion of 4.95 ± 0.65%). T. fusca was induced by xylan mainly to secrete a xylanase from GH11 family (W8GGR4, GenBank AHK22788.1; with relative secretion of 8.71 ± 3.83%) which could rapidly degrade xylan to xylo-oligosaccharide (XOS) and xylose within 2 min, while high concentrations (>0.5%, w/v) of XOS or xylose suppressed the growth of T. fusca; which may be the reason why T. fusca unable to grow alone in corn stalk solid medium. However, T. lanuginosus could utilize the XOS and xylose produced by xylanases secreted by T. fusca. During the synergistic degradation of lignocellulose by T. lanuginosus and T. fusca, xylan was rapidly consumed by T. lanuginosus, the residual cellulose could specifically induced T. fusca to express a GH10 xylanase with a CBM2 domain (Q47KR6, GenBank AAZ56956.1; with relative secretion of 5.03 ± 1.33%) and 6 cellulases (2 exocellulases and 4 endocellulases). Moreover, T. lanuginosus increased the secretion of cellulases from T. fusca by 19-25%. The order of T. lanuginosus and T. fusca was consistent with the multilayered structures of lignocellulose and could be regulated by different concentrations of XOS and xylose. The novel synergism of T. lanuginosus and T. fusca gave a new sight for revealing more synergetic relationships in natural environments and exploring efficient microbial inoculants and enzyme cocktails for lignocellulose degradation.
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Affiliation(s)
- Zelu Shi
- State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao, China
| | - Chao Han
- State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao, China
| | - Xiujun Zhang
- State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao, China
| | - Li Tian
- State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao, China
| | - Lushan Wang
- State Key Laboratory of Microbial Technology, Microbial Technology Institute, Shandong University, Qingdao, China
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14
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Nibbering P, Petersen BL, Motawia MS, Jørgensen B, Ulvskov P, Niittylä T. Golgi-localized exo-β1,3-galactosidases involved in cell expansion and root growth in Arabidopsis. J Biol Chem 2020; 295:10581-10592. [PMID: 32493777 DOI: 10.1074/jbc.ra120.013878] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 05/29/2020] [Indexed: 12/20/2022] Open
Abstract
Plant arabinogalactan proteins (AGPs) are a diverse group of cell surface- and wall-associated glycoproteins. Functionally important AGP glycans are synthesized in the Golgi apparatus, but the relationships among their glycosylation levels, processing, and functionalities are poorly understood. Here, we report the identification and functional characterization of two Golgi-localized exo-β-1,3-galactosidases from the glycosyl hydrolase 43 (GH43) family in Arabidopsis thaliana GH43 loss-of-function mutants exhibited root cell expansion defects in sugar-containing growth media. This root phenotype was associated with an increase in the extent of AGP cell wall association, as demonstrated by Yariv phenylglycoside dye quantification and comprehensive microarray polymer profiling of sequentially extracted cell walls. Characterization of recombinant GH43 variants revealed that the exo-β-1,3-galactosidase activity of GH43 enzymes is hindered by β-1,6 branches on β-1,3-galactans. In line with this steric hindrance, the recombinant GH43 variants did not release galactose from cell wall-extracted glycoproteins or AGP-rich gum arabic. These results indicate that the lack of exo-β-1,3-galactosidase activity alters cell wall extensibility in roots, a phenotype that could be explained by the involvement of galactosidases in AGP glycan biosynthesis.
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Affiliation(s)
- Pieter Nibbering
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Bent L Petersen
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Mohammed Saddik Motawia
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Bodil Jørgensen
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Peter Ulvskov
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Totte Niittylä
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Centre, Swedish University of Agricultural Sciences, Umeå, Sweden
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15
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Kuki H, Yokoyama R, Kuroha T, Nishitani K. Xyloglucan Is Not Essential for the Formation and Integrity of the Cellulose Network in the Primary Cell Wall Regenerated from Arabidopsis Protoplasts. PLANTS (BASEL, SWITZERLAND) 2020; 9:E629. [PMID: 32423049 PMCID: PMC7285283 DOI: 10.3390/plants9050629] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/24/2020] [Accepted: 05/12/2020] [Indexed: 01/01/2023]
Abstract
The notion that xyloglucans (XG) play a pivotal role in tethering cellulose microfibrils in the primary cell wall of plants can be traced back to the first molecular model of the cell wall proposed in 1973, which was reinforced in the 1990s by the identification of Xyloglucan Endotransglucosylase/Hydrolase (XTH) enzymes that cleave and reconnect xyloglucan crosslinks in the cell wall. However, this tethered network model has been seriously challenged since 2008 by the identification of the Arabidopsis thaliana xyloglucan-deficient mutant (xxt1 xxt2), which exhibits functional cell walls. Thus, the molecular mechanism underlying the physical integration of cellulose microfibrils into the cell wall remains controversial. To resolve this dilemma, we investigated the cell wall regeneration process using mesophyll protoplasts derived from xxt1 xxt2 mutant leaves. Imaging analysis revealed only a slight difference in the structure of cellulose microfibril network between xxt1 xxt2 and wild-type (WT) protoplasts. Additionally, exogenous xyloglucan application did not alter the cellulose deposition patterns or mechanical stability of xxt1 xxt2 mutant protoplasts. These results indicate that xyloglucan is not essential for the initial assembly of the cellulose network, and the cellulose network formed in the absence of xyloglucan provides sufficient tensile strength to the primary cell wall regenerated from protoplasts.
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Affiliation(s)
- Hiroaki Kuki
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan; (H.K.); (R.Y.); (T.K.)
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan
| | - Ryusuke Yokoyama
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan; (H.K.); (R.Y.); (T.K.)
| | - Takeshi Kuroha
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan; (H.K.); (R.Y.); (T.K.)
- Division of Applied Genetics, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization (NARO), Tsukuba, Ibaraki 305-8604, Japan
| | - Kazuhiko Nishitani
- Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan; (H.K.); (R.Y.); (T.K.)
- Department of Biological Science, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka, Kanagawa 259-1293, Japan
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16
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BIDHENDI A, CHEBLI Y, GEITMANN A. Fluorescence visualization of cellulose and pectin in the primary plant cell wall. J Microsc 2020; 278:164-181. [DOI: 10.1111/jmi.12895] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/07/2020] [Accepted: 04/06/2020] [Indexed: 12/12/2022]
Affiliation(s)
- A.J. BIDHENDI
- Department of Plant ScienceMcGill UniversityMacdonald Campus Ste‐Anne‐de‐Bellevue Québec Canada
| | - Y. CHEBLI
- Department of Plant ScienceMcGill UniversityMacdonald Campus Ste‐Anne‐de‐Bellevue Québec Canada
| | - A. GEITMANN
- Department of Plant ScienceMcGill UniversityMacdonald Campus Ste‐Anne‐de‐Bellevue Québec Canada
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17
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Dal Santo S, Tucker MR, Tan HT, Burbidge CA, Fasoli M, Böttcher C, Boss PK, Pezzotti M, Davies C. Auxin treatment of grapevine (Vitis vinifera L.) berries delays ripening onset by inhibiting cell expansion. PLANT MOLECULAR BIOLOGY 2020; 103:91-111. [PMID: 32043226 DOI: 10.1007/s11103-020-00977-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 02/04/2020] [Indexed: 05/08/2023]
Abstract
Auxin treatment of grape (Vitis vinifera L.) berries delays ripening by inducing changes in gene expression and cell wall metabolism and could combat some deleterious climate change effects. Auxins are inhibitors of grape berry ripening and their application may be useful to delay harvest to counter effects of climate change. However, little is known about how this delay occurs. The expression of 1892 genes was significantly changed compared to the control during a 48 h time-course where the auxin 1-naphthaleneacetic acid (NAA) was applied to pre-veraison grape berries. Principal component analysis showed that the control and auxin-treated samples were most different at 3 h post-treatment when approximately three times more genes were induced than repressed by NAA. There was considerable cross-talk between hormone pathways, particularly between those of auxin and ethylene. Decreased expression of genes encoding putative cell wall catabolic enzymes (including those involved with pectin) and increased expression of putative cellulose synthases indicated that auxins may preserve cell wall structure. This was confirmed by immunochemical labelling of berry sections using antibodies that detect homogalacturonan (LM19) and methyl-esterified homogalacturonan (LM20) and by labelling with the CMB3a cellulose-binding module. Comparison of the auxin-induced changes in gene expression with the pattern of these genes during berry ripening showed that the effect on transcription is a mix of changes that may specifically alter the progress of berry development in a targeted manner and others that could be considered as non-specific changes. Several lines of evidence suggest that cell wall changes and associated berry softening are the first steps in ripening and that delaying cell expansion can delay ripening providing a possible mechanism for the observed auxin effects.
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Affiliation(s)
- Silvia Dal Santo
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
| | - Matthew R Tucker
- School of Agriculture, Food and Wine, Level 4, Main WIC Building, University of Adelaide, Waite Campus, Urrbrae, SA, 5064, Australia
| | - Hwei-Ting Tan
- School of Agriculture, Food and Wine, Level 4, Main WIC Building, University of Adelaide, Waite Campus, Urrbrae, SA, 5064, Australia
| | - Crista A Burbidge
- CSIRO Agriculture and Food, Locked Bag 2, Glen Osmond, SA, 5064, Australia
| | - Marianna Fasoli
- E. & J. Gallo Winery, 600 Yosemite Blvd, Modesto, CA, 95354, USA
| | - Christine Böttcher
- CSIRO Agriculture and Food, Locked Bag 2, Glen Osmond, SA, 5064, Australia
| | - Paul K Boss
- CSIRO Agriculture and Food, Locked Bag 2, Glen Osmond, SA, 5064, Australia
| | - Mario Pezzotti
- Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy
| | - Christopher Davies
- CSIRO Agriculture and Food, Locked Bag 2, Glen Osmond, SA, 5064, Australia.
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18
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Levi Hevroni B, Moraïs S, Ben-David Y, Morag E, Bayer EA. Minimalistic Cellulosome of the Butanologenic Bacterium Clostridium saccharoperbutylacetonicum. mBio 2020; 11:e00443-20. [PMID: 32234813 PMCID: PMC7157769 DOI: 10.1128/mbio.00443-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 03/05/2020] [Indexed: 12/31/2022] Open
Abstract
Clostridium saccharoperbutylacetonicum is a mesophilic, anaerobic, butanol-producing bacterium, originally isolated from soil. It was recently reported that C. saccharoperbutylacetonicum possesses multiple cellulosomal elements and would potentially form the smallest cellulosome known in nature. Its genome contains only eight dockerin-bearing enzymes, and its unique scaffoldin bears two cohesins (Cohs), three X2 modules, and two carbohydrate-binding modules (CBMs). In this study, all of the cellulosome-related modules were cloned, expressed, and purified. The recombinant cohesins, dockerins, and CBMs were tested for binding activity using enzyme-linked immunosorbent assay (ELISA)-based techniques. All the enzymes were tested for their comparative enzymatic activity on seven different cellulosic and hemicellulosic substrates, thus revealing four cellulases, a xylanase, a mannanase, a xyloglucanase, and a lichenase. All dockerin-containing enzymes interacted similarly with the second cohesin (Coh2) module, whereas Coh1 was more restricted in its interaction pattern. In addition, the polysaccharide-binding properties of the CBMs within the scaffoldin were examined by two complementary assays, affinity electrophoresis and affinity pulldown. The scaffoldin of C. saccharoperbutylacetonicum exhibited high affinity for cellulosic and hemicellulosic substrates, specifically to microcrystalline cellulose and xyloglucan. Evidence that supports substrate-dependent in vivo secretion of cellulosomes is presented. The results of our analyses contribute to a better understanding of simple cellulosome systems by identifying the key players in this minimalistic system and the binding pattern of its cohesin-dockerin interaction. The knowledge gained by our study will assist further exploration of similar minimalistic cellulosomes and will contribute to the significance of specific sets of defined cellulosomal enzymes in the degradation of cellulosic biomass.IMPORTANCE Cellulosome-producing bacteria are considered among the most important bacteria in both mesophilic and thermophilic environments, owing to their capacity to deconstruct recalcitrant plant-derived polysaccharides (and notably cellulose) into soluble saccharides for subsequent processing. In many ecosystems, the cellulosome-producing bacteria are particularly effective "first responders." The massive amounts of sugars produced are potentially amenable in industrial settings to further fermentation by appropriate microbes to biofuels, notably ethanol and butanol. Among the solvent-producing bacteria, Clostridium saccharoperbutylacetonicum has the smallest cellulosome system known thus far. The importance of investigating the building blocks of such a small, multifunctional nanomachine is crucial to understanding the fundamental activities of this efficient enzymatic complex.
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Affiliation(s)
- Bosmat Levi Hevroni
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Sarah Moraïs
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Yonit Ben-David
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Ely Morag
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Edward A Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
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19
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Behr M, Faleri C, Hausman JF, Planchon S, Renaut J, Cai G, Guerriero G. Distribution of cell-wall polysaccharides and proteins during growth of the hemp hypocotyl. PLANTA 2019; 250:1539-1556. [PMID: 31352512 DOI: 10.1007/s00425-019-03245-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/18/2019] [Indexed: 05/13/2023]
Abstract
The immuno-ultrastructural investigation localized cell-wall polysaccharides of bast fibers during hemp hypocotyl growth. Moreover, for the first time, the localization of a peroxidase and laccase is provided in textile hemp. In the hypocotyl of textile hemp, elongation and girth increase are separated in time. This organ is therefore ideal for time-course analyses. Here, we follow the ultrastructural rearrangement of cell-wall components during the development of the hemp hypocotyl. An expression analysis of genes involved in the biosynthesis of cellulose, the chief polysaccharide of bast fiber cell walls and xylan, the main hemicellulose of secondary cell walls, is also provided. The analysis shows a higher expression of cellulose and xylan-related genes at 15 and 20 days after sowing, as compared to 9 days. In the young hypocotyl, the cell walls of bast fibers show cellulose microfibrils that are not yet compacted to form a mature G-layer. Crystalline cellulose is detected abundantly in the S1-layer, together with unsubstituted/low-substituted xylan and, to a lesser extent, in the G-layer. The LM5 galactan epitope is confined to the walls of parenchymatic cells. LM6-specific arabinans are detected at the interface between the cytoplasm and the gelatinous cell wall of bast fibers. The class III peroxidase antibody shows localization in the G-layer only at older developmental stages. The laccase antibody shows a distinctive labelling of the G-layer region closest to the S1-layer; the signal becomes more homogeneous as the hypocotyl matures. The data provide important insights on the cell wall distribution of polysaccharide and protein components in bast fibers during the hypocotyl growth of textile hemp.
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Affiliation(s)
- Marc Behr
- Research and Innovation Department, Luxembourg Institute of Science and Technology, 5 Avenue des Hauts-Fourneaux, 4362, Esch/Alzette, Luxembourg
| | - Claudia Faleri
- Department of Life Sciences, University of Siena, via P.A. Mattioli 4, 53100, Siena, Italy
| | - Jean-Francois Hausman
- Research and Innovation Department, Luxembourg Institute of Science and Technology, 5 Avenue des Hauts-Fourneaux, 4362, Esch/Alzette, Luxembourg
| | - Sébastien Planchon
- Research and Innovation Department, Luxembourg Institute of Science and Technology, 5 Avenue des Hauts-Fourneaux, 4362, Esch/Alzette, Luxembourg
| | - Jenny Renaut
- Research and Innovation Department, Luxembourg Institute of Science and Technology, 5 Avenue des Hauts-Fourneaux, 4362, Esch/Alzette, Luxembourg
| | - Giampiero Cai
- Department of Life Sciences, University of Siena, via P.A. Mattioli 4, 53100, Siena, Italy.
| | - Gea Guerriero
- Research and Innovation Department, Luxembourg Institute of Science and Technology, 5 Avenue des Hauts-Fourneaux, 4362, Esch/Alzette, Luxembourg.
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20
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Mosina NL, Schubert WD, Cowan DA. Characterization and homology modelling of a novel multi-modular and multi-functional Paenibacillus mucilaginosus glycoside hydrolase. Extremophiles 2019; 23:681-686. [PMID: 31372752 DOI: 10.1007/s00792-019-01121-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 07/21/2019] [Indexed: 10/26/2022]
Abstract
Glycoside hydrolases, particularly cellulases, xylanases and mannanases, are essential for the depolymerisation of lignocellulosic substrates in various industrial bio-processes. In the present study, a novel glycoside hydrolase from Paenibacillus mucilaginosus (PmGH) was expressed in E. coli, purified and characterised. Functional analysis indicated that PmGH is a 130 kDa thermophilic multi-modular and multi-functional enzyme, comprising a GH5, a GH6 and two CBM3 domains and exhibiting cellulase, mannanase and xylanase activities. The enzyme displayed optimum hydrolytic activities at pH 6 and 60 °C and moderate thermostability. Homology modelling of the full-length protein highlighted the structural and functional novelty of native PmGH, with no close structural homologs identified. However, homology modelling of the individual GH5, GH6 and the two CBM3 domains yielded excellent models based on related structures from the Protein Data Bank. The catalytic GH5 and GH6 domains displayed a (β/α)8 and a distorted seven stranded (β/α) fold, respectively. The distinct homology at the domain level but low homology of the full-length protein suggests that this protein evolved by exogenous gene acquisition and recombination.
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Affiliation(s)
- Ntsoaki Leticia Mosina
- Department Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Lynnwood Road, Hatfield, Pretoria, 0002, South Africa
| | - Wolf-Dieter Schubert
- Department Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Lynnwood Road, Hatfield, Pretoria, 0002, South Africa
| | - Don A Cowan
- Department Biochemistry, Genetics and Microbiology, Centre for Microbial Ecology and Genomics, University of Pretoria, Lynnwood Road, Hatfield, Pretoria, 0002, South Africa.
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21
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Cell surface display of proteins on filamentous fungi. Appl Microbiol Biotechnol 2019; 103:6949-6972. [PMID: 31359105 DOI: 10.1007/s00253-019-10026-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 07/11/2019] [Accepted: 07/15/2019] [Indexed: 12/14/2022]
Abstract
Protein display approaches have been useful to endow the cell surface of yeasts with new catalytic activities so that they can act as enhanced whole-cell biocatalysts. Despite their biotechnological potential, protein display technologies remain poorly developed for filamentous fungi. The lignocellulolytic character of some of them coupled to the cell surface biosynthesis of valuable molecules by a single or a cascade of several displayed enzymes is an appealing prospect. Cell surface protein display consists in the co-translational fusion of a functional protein (passenger) to an anchor one, usually a cell-wall-resident protein. The abundance, spacing, and local environment of the displayed enzymes-determined by the relationship of the anchor protein with the structure and dynamics of the engineered cell wall-are factors that influence the performance of display-based biocatalysts. The development of protein display strategies in filamentous fungi could be based on the field advances in yeasts; however, the unique composition, structure, and biology of filamentous fungi cell walls require the customization of the approach to those microorganisms. In this prospective review, the cellular bases, the design principles, and the available tools to foster the development of cell surface protein display technologies in filamentous fungi are discussed.
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22
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Midorikawa K, Kuroda M, Yamashita H, Tamura T, Abe K, Asakura T. Oryza sativa Brittle Culm 1-like 6 modulates β-glucan levels in the endosperm cell wall. PLoS One 2019; 14:e0217212. [PMID: 31120929 PMCID: PMC6532911 DOI: 10.1371/journal.pone.0217212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Accepted: 05/07/2019] [Indexed: 11/18/2022] Open
Abstract
The endosperm cell wall affects post-harvest grain quality by affecting the mechanical fragility and water absorption of the grain. Therefore, understanding the mechanism underlying endosperm cell wall synthesis is important for determining the growth and quality of cereals. However, the molecular machinery mediating endosperm cell wall biosynthesis is not well understood. In this study, we investigated the role of Oryza sativa Brittle Culm 1-like 6 (OsBC1L6), a member of the COBRA-like protein family, in cellulose synthesis in rice. OsBC1L6 mRNA was expressed in ripening seeds during endosperm enlargement. When OsBC1L6-RFP was expressed in Arabidopsis cell cultures, this fusion protein was transported to the plasma membrane. To investigate the target molecules of OsBC1L6, we analyzed the binding interactions of OsBC1L6 with cellohexaose and the analogs using surface plasmon resonance, determining that cellohexaose bound to OsBC1L6. The β-glucan contents were significantly reduced in OsBC1L6-RNAi calli and OsBC1L6-deficient seeds from a Tos insertion mutant, compared to their wild-type counterparts. These findings suggest that OsBC1L6 modulates β-glucan synthesis during endosperm cell wall formation by interacting with cellulose moieties on the plasma membrane during seed ripening.
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Affiliation(s)
- Keiko Midorikawa
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Masaharu Kuroda
- Division of Crop Development, Central Region Agricultural Research Center, National Agriculture and Food Research Organization (NARO), Niigata, Japan
- * E-mail: (TA); (MK)
| | - Haruyuki Yamashita
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
| | - Tomoko Tamura
- Department of Nutritional Science and Food Safety, Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo, Japan
| | - Keiko Abe
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- Kanagawa Institute of Industrial Science and Technology (KISTEC), Life Science & Environmental Research Center (LiSE), Kanagawa, Japan
| | - Tomiko Asakura
- Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- * E-mail: (TA); (MK)
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23
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Guo X, Runavot JL, Bourot S, Meulewaeter F, Hernandez-Gomez M, Holland C, Harholt J, Willats WGT, Mravec J, Knox P, Ulvskov P. Metabolism of polysaccharides in dynamic middle lamellae during cotton fibre development. PLANTA 2019; 249:1565-1581. [PMID: 30737556 DOI: 10.1007/s00425-019-03107-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 02/04/2019] [Indexed: 06/09/2023]
Abstract
Evidence is presented that cotton fibre adhesion and middle lamella formation are preceded by cutin dilution and accompanied by rhamnogalacturonan-I metabolism. Cotton fibres are single cell structures that early in development adhere to one another via the cotton fibre middle lamella (CFML) to form a tissue-like structure. The CFML is disassembled around the time of initial secondary wall deposition, leading to fibre detachment. Observations of CFML in the light microscope have suggested that the development of the middle lamella is accompanied by substantial cell-wall metabolism, but it has remained an open question as to which processes mediate adherence and which lead to detachment. The mechanism of adherence and detachment were investigated here using glyco-microarrays probed with monoclonal antibodies, transcript profiling, and observations of fibre auto-digestion. The results suggest that adherence is brought about by cutin dilution, while the presence of relevant enzyme activities and the dynamics of rhamnogalacturonan-I side-chain accumulation and disappearance suggest that both attachment and detachment are accompanied by rhamnogalacturonan-I metabolism.
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Affiliation(s)
- Xiaoyuan Guo
- Department of Plant and Environmental Sciences, Copenhagen University, Frederiksberg, Denmark
| | - Jean-Luc Runavot
- Bayer CropScience NV, Innovation Center, Technologiepark 38, 9052, Ghent, Belgium
| | - Stéphane Bourot
- Bayer CropScience NV, Innovation Center, Technologiepark 38, 9052, Ghent, Belgium
| | - Frank Meulewaeter
- Bayer CropScience NV, Innovation Center, Technologiepark 38, 9052, Ghent, Belgium
| | - Mercedes Hernandez-Gomez
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Claire Holland
- Department of Plant and Environmental Sciences, Copenhagen University, Frederiksberg, Denmark
| | - Jesper Harholt
- Department of Plant and Environmental Sciences, Copenhagen University, Frederiksberg, Denmark
| | - William G T Willats
- School of Agriculture, Food and Rural Development, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Jozef Mravec
- Department of Plant and Environmental Sciences, Copenhagen University, Frederiksberg, Denmark
| | - Paul Knox
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Peter Ulvskov
- Department of Plant and Environmental Sciences, Copenhagen University, Frederiksberg, Denmark.
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24
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Investigating the relationship between cell wall polysaccharide composition and the extractability of grape phenolic compounds into Shiraz wines. Part II: Extractability during fermentation into wines made from grapes of different ripeness levels. Food Chem 2019; 278:26-35. [DOI: 10.1016/j.foodchem.2018.10.136] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 09/26/2018] [Accepted: 10/29/2018] [Indexed: 11/23/2022]
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25
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Garrido-Bañuelos G, Buica A, Schückel J, Zietsman AJ, Willats WG, Moore JP, Du Toit WJ. Investigating the relationship between grape cell wall polysaccharide composition and the extractability of phenolic compounds into Shiraz wines. Part I: Vintage and ripeness effects. Food Chem 2019; 278:36-46. [DOI: 10.1016/j.foodchem.2018.10.134] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 09/26/2018] [Accepted: 10/29/2018] [Indexed: 10/28/2022]
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26
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Francin-Allami M, Alvarado C, Daniel S, Geairon A, Saulnier L, Guillon F. Spatial and temporal distribution of cell wall polysaccharides during grain development of Brachypodium distachyon. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 280:367-382. [PMID: 30824016 DOI: 10.1016/j.plantsci.2018.12.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 12/14/2018] [Accepted: 12/15/2018] [Indexed: 06/09/2023]
Abstract
Brachypodium distachyon (Brachypodium) is now well considered as being a suitable plant model for studying temperate cereal crops. Its cell walls are phylogenetically intermediate between rice and poaceae, with a greater proximity to these latter. By microscopic and biochemical approaches, this work gives an overview of the temporal and spatial distribution of cell wall polysaccharides in the grain of Brachypodium from the end of the cellularization step to the maturation of grain. Variation in arabinoxylan chemical structure and distribution were demonstrated according to development and different grain tissues. In particular, the kinetic of arabinoxylan feruloylation was shown occuring later in the aleurone layers compared to storage endosperm. Mixed linked β-glucan was detected in whole the tissues of Brachypodium grain even at late stage of development. Cellulose was found in both the storage endosperm and the outer layers. Homogalacturonan and rhamnogalacturonan I epitopes were differentially distributed within the grain tissues. LM5 galactan epitope was restricted to the aleurone layers contrary to LM6 arabinan epitope which was detected in the whole endosperm. A massive deposition of highly methylated homogalacturonans in vesicular bodies was observed underneath the cell wall of the testa t2 layer at early stage of development. At maturity, low-methylated homogalacturonans totally fulfilled the lumen of the t2 cell layer, suggesting pectin remodeling during grain development. Xyloglucans were only detected in the cuticle above the testa early in the development of the grain while feruloylated arabinoxylans were preferentially deposited into the cell wall of t1 layer. Indeed, the circumscribed distribution of some of the cell wall polysaccharides raises questions about their role in grain development and physiology.
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Affiliation(s)
| | - Camille Alvarado
- INRA, UR 1268 Biopolymères Interactions Assemblages, 44000, Nantes, France
| | - Sylviane Daniel
- INRA, UR 1268 Biopolymères Interactions Assemblages, 44000, Nantes, France
| | - Audrey Geairon
- INRA, UR 1268 Biopolymères Interactions Assemblages, 44000, Nantes, France
| | - Luc Saulnier
- INRA, UR 1268 Biopolymères Interactions Assemblages, 44000, Nantes, France
| | - Fabienne Guillon
- INRA, UR 1268 Biopolymères Interactions Assemblages, 44000, Nantes, France
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27
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Gartaula G, Dhital S, Netzel G, Flanagan BM, Yakubov GE, Beahan CT, Collins HM, Burton RA, Bacic A, Gidley MJ. Quantitative structural organisation model for wheat endosperm cell walls: Cellulose as an important constituent. Carbohydr Polym 2018; 196:199-208. [DOI: 10.1016/j.carbpol.2018.05.041] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 05/11/2018] [Accepted: 05/12/2018] [Indexed: 12/01/2022]
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28
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Voiniciuc C, Pauly M, Usadel B. Monitoring Polysaccharide Dynamics in the Plant Cell Wall. PLANT PHYSIOLOGY 2018; 176:2590-2600. [PMID: 29487120 PMCID: PMC5884611 DOI: 10.1104/pp.17.01776] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/07/2018] [Indexed: 05/18/2023]
Abstract
New technologies reveal the deposition and remodeling of plant cell wall polysaccharides and their impact on plant development.
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Affiliation(s)
- Cătălin Voiniciuc
- Institute for Plant Cell Biology and Biotechnology and Cluster of Excellence on Plant Sciences, Heinrich Heine University, 40225 Duesseldorf, Germany
| | - Markus Pauly
- Institute for Plant Cell Biology and Biotechnology and Cluster of Excellence on Plant Sciences, Heinrich Heine University, 40225 Duesseldorf, Germany
| | - Björn Usadel
- Institute for Biology I, BioSC, RWTH Aachen University, 52074 Aachen, Germany
- Forschungszentum Jülich, IBG-2 Plant Sciences, 52428 Juelich, Germany
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29
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Rydahl MG, Hansen AR, Kračun SK, Mravec J. Report on the Current Inventory of the Toolbox for Plant Cell Wall Analysis: Proteinaceous and Small Molecular Probes. FRONTIERS IN PLANT SCIENCE 2018; 9:581. [PMID: 29774041 PMCID: PMC5943554 DOI: 10.3389/fpls.2018.00581] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/13/2018] [Indexed: 05/18/2023]
Abstract
Plant cell walls are highly complex structures composed of diverse classes of polysaccharides, proteoglycans, and polyphenolics, which have numerous roles throughout the life of a plant. Significant research efforts aim to understand the biology of this cellular organelle and to facilitate cell-wall-based industrial applications. To accomplish this, researchers need to be provided with a variety of sensitive and specific detection methods for separate cell wall components, and their various molecular characteristics in vitro as well as in situ. Cell wall component-directed molecular detection probes (in short: cell wall probes, CWPs) are an essential asset to the plant glycobiology toolbox. To date, a relatively large set of CWPs has been produced-mainly consisting of monoclonal antibodies, carbohydrate-binding modules, synthetic antibodies produced by phage display, and small molecular probes. In this review, we summarize the state-of-the-art knowledge about these CWPs; their classification and their advantages and disadvantages in different applications. In particular, we elaborate on the recent advances in non-conventional approaches to the generation of novel CWPs, and identify the remaining gaps in terms of target recognition. This report also highlights the addition of new "compartments" to the probing toolbox, which is filled with novel chemical biology tools, such as metabolic labeling reagents and oligosaccharide conjugates. In the end, we also forecast future developments in this dynamic field.
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Affiliation(s)
- Maja G. Rydahl
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Aleksander R. Hansen
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Stjepan K. Kračun
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
- GlycoSpot IVS, Frederiksberg, Denmark
| | - Jozef Mravec
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, Denmark
- *Correspondence: Jozef Mravec
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30
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Zheng Y, Wang X, Chen Y, Wagner E, Cosgrove DJ. Xyloglucan in the primary cell wall: assessment by FESEM, selective enzyme digestions and nanogold affinity tags. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 93:211-226. [PMID: 29160933 DOI: 10.1111/tpj.13778] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 11/02/2017] [Accepted: 11/06/2017] [Indexed: 05/02/2023]
Abstract
Xyloglucan has been hypothesized to bind extensively to cellulose microfibril surfaces and to tether microfibrils into a load-bearing network, thereby playing a central role in wall mechanics and growth, but this view is challenged by newer results. Here we combined high-resolution imaging by field emission scanning electron microscopy (FESEM) with nanogold affinity tags and selective endoglucanase treatments to assess the spatial location and conformation of xyloglucan in onion cell walls. FESEM imaging of xyloglucanase-digested cell walls revealed an altered microfibril organization but did not yield clear evidence of xyloglucan conformations. Backscattered electron detection provided excellent detection of nanogold affinity tags in the context of wall fibrillar organization. Labelling with xyloglucan-specific CBM76 conjugated with nanogold showed that xyloglucans were associated with fibril surfaces in both extended and coiled conformations, but tethered configurations were not observed. Labelling with nanogold-conjugated CBM3, which binds the hydrophobic surface of crystalline cellulose, was infrequent until the wall was predigested with xyloglucanase, whereupon microfibril labelling was extensive. When tamarind xyloglucan was allowed to bind to xyloglucan-depleted onion walls, CBM76 labelling gave positive evidence for xyloglucans in both extended and coiled conformations, yet xyloglucan chains were not directly visible by FESEM. These results indicate that an appreciable, but still small, surface of cellulose microfibrils in the onion wall is tightly bound with extended xyloglucan chains and that some of the xyloglucan has a coiled conformation.
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Affiliation(s)
- Yunzhen Zheng
- Center for Lignocellulose Structure and Formation, Penn State University, University Park, PA, 16802, USA
- Department of Biology, Penn State University, University Park, PA, 16802, USA
| | - Xuan Wang
- Center for Lignocellulose Structure and Formation, Penn State University, University Park, PA, 16802, USA
- Department of Biology, Penn State University, University Park, PA, 16802, USA
| | - Yuning Chen
- Department of Biology, Penn State University, University Park, PA, 16802, USA
| | - Edward Wagner
- Department of Biology, Penn State University, University Park, PA, 16802, USA
| | - Daniel J Cosgrove
- Center for Lignocellulose Structure and Formation, Penn State University, University Park, PA, 16802, USA
- Department of Biology, Penn State University, University Park, PA, 16802, USA
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31
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Affiliation(s)
- R. Rashmi
- Institute of Bioinformatics and Applied Biotechnology, Bengaluru, India
| | - K. R. Siddalingamurthy
- Department of Biochemistry, Jnanabharathi Campus, Bangalore University, Bengaluru, India
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32
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Pires VMR, Pereira PMM, Brás JLA, Correia M, Cardoso V, Bule P, Alves VD, Najmudin S, Venditto I, Ferreira LMA, Romão MJ, Carvalho AL, Fontes CMGA, Prazeres DM. Stability and Ligand Promiscuity of Type A Carbohydrate-binding Modules Are Illustrated by the Structure of Spirochaeta thermophila StCBM64C. J Biol Chem 2017; 292:4847-4860. [PMID: 28179427 DOI: 10.1074/jbc.m116.767541] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 02/07/2017] [Indexed: 11/06/2022] Open
Abstract
Deconstruction of cellulose, the most abundant plant cell wall polysaccharide, requires the cooperative activity of a large repertoire of microbial enzymes. Modular cellulases contain non-catalytic type A carbohydrate-binding modules (CBMs) that specifically bind to the crystalline regions of cellulose, thus promoting enzyme efficacy through proximity and targeting effects. Although type A CBMs play a critical role in cellulose recycling, their mechanism of action remains poorly understood. Here we produced a library of recombinant CBMs representative of the known diversity of type A modules. The binding properties of 40 CBMs, in fusion with an N-terminal GFP domain, revealed that type A CBMs possess the ability to recognize different crystalline forms of cellulose and chitin over a wide range of temperatures, pH levels, and ionic strengths. A Spirochaeta thermophila CBM64, in particular, displayed plasticity in its capacity to bind both crystalline and soluble carbohydrates under a wide range of extreme conditions. The structure of S. thermophila StCBM64C revealed an untwisted, flat, carbohydrate-binding interface comprising the side chains of four tryptophan residues in a co-planar linear arrangement. Significantly, two highly conserved asparagine side chains, each one located between two tryptophan residues, are critical to insoluble and soluble glucan recognition but not to bind xyloglucan. Thus, CBM64 compact structure and its extended and versatile ligand interacting platform illustrate how type A CBMs target their appended plant cell wall-degrading enzymes to a diversity of recalcitrant carbohydrates under a wide range of environmental conditions.
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Affiliation(s)
- Virgínia M R Pires
- From the CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário da Ajuda, 1300-477 Lisboa, Portugal
| | - Pedro M M Pereira
- the Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
| | - Joana L A Brás
- From the CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário da Ajuda, 1300-477 Lisboa, Portugal.,NZYTech Genes Enzymes, 1649-038 Lisboa, Portugal, and
| | - Márcia Correia
- the UCIBIO-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Vânia Cardoso
- From the CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário da Ajuda, 1300-477 Lisboa, Portugal.,NZYTech Genes Enzymes, 1649-038 Lisboa, Portugal, and
| | - Pedro Bule
- From the CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário da Ajuda, 1300-477 Lisboa, Portugal
| | - Victor D Alves
- From the CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário da Ajuda, 1300-477 Lisboa, Portugal
| | - Shabir Najmudin
- From the CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário da Ajuda, 1300-477 Lisboa, Portugal
| | - Immacolata Venditto
- From the CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário da Ajuda, 1300-477 Lisboa, Portugal
| | - Luís M A Ferreira
- From the CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário da Ajuda, 1300-477 Lisboa, Portugal.,NZYTech Genes Enzymes, 1649-038 Lisboa, Portugal, and
| | - Maria João Romão
- the UCIBIO-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Ana Luísa Carvalho
- the UCIBIO-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Carlos M G A Fontes
- From the CIISA, Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário da Ajuda, 1300-477 Lisboa, Portugal, .,NZYTech Genes Enzymes, 1649-038 Lisboa, Portugal, and
| | - Duarte Miguel Prazeres
- the Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal,
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33
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Cockburn D, Wilkens C, Dilokpimol A, Nakai H, Lewińska A, Abou Hachem M, Svensson B. Using Carbohydrate Interaction Assays to Reveal Novel Binding Sites in Carbohydrate Active Enzymes. PLoS One 2016; 11:e0160112. [PMID: 27504624 PMCID: PMC4978508 DOI: 10.1371/journal.pone.0160112] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 07/13/2016] [Indexed: 01/23/2023] Open
Abstract
Carbohydrate active enzymes often contain auxiliary binding sites located either on independent domains termed carbohydrate binding modules (CBMs) or as so-called surface binding sites (SBSs) on the catalytic module at a certain distance from the active site. The SBSs are usually critical for the activity of their cognate enzyme, though they are not readily detected in the sequence of a protein, but normally require a crystal structure of a complex for their identification. A variety of methods, including affinity electrophoresis (AE), insoluble polysaccharide pulldown (IPP) and surface plasmon resonance (SPR) have been used to study auxiliary binding sites. These techniques are complementary as AE allows monitoring of binding to soluble polysaccharides, IPP to insoluble polysaccharides and SPR to oligosaccharides. Here we show that these methods are useful not only for analyzing known binding sites, but also for identifying new ones, even without structural data available. We further verify the chosen assays discriminate between known SBS/CBM containing enzymes and negative controls. Altogether 35 enzymes are screened for the presence of SBSs or CBMs and several novel binding sites are identified, including the first SBS ever reported in a cellulase. This work demonstrates that combinations of these methods can be used as a part of routine enzyme characterization to identify new binding sites and advance the study of SBSs and CBMs, allowing them to be detected in the absence of structural data.
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Affiliation(s)
- Darrell Cockburn
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
| | - Casper Wilkens
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
| | - Adiphol Dilokpimol
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
| | - Hiroyuki Nakai
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
| | - Anna Lewińska
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
| | - Maher Abou Hachem
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
| | - Birte Svensson
- Enzyme and Protein Chemistry, Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark
- * E-mail:
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Recent structural insights into the enzymology of the ubiquitous plant cell wall glycan xyloglucan. Curr Opin Struct Biol 2016; 40:43-53. [PMID: 27475238 DOI: 10.1016/j.sbi.2016.07.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 07/05/2016] [Accepted: 07/06/2016] [Indexed: 01/03/2023]
Abstract
The xyloglucans (XyGs) constitute a family of highly decorated β(1→4)-glucans whose members are widespread and abundant across the plant kingdom. As such, XyGs constitute a significant reserve of metabolically accessible monosaccharides for diverse phytopathogenic, saprophytic, and gut symbiotic micro-organisms. To overcome the intrinsic stability of the diverse glycosidic bonds in XyGs, bacteria and fungi have evolved extensive repertoires of xyloglucan-active enzymes from manifold families, whose exquisitely adapted tertiary structures are recently coming to light.
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Attia M, Stepper J, Davies GJ, Brumer H. Functional and structural characterization of a potent GH74 endo-xyloglucanase from the soil saprophyte Cellvibrio japonicus unravels the first step of xyloglucan degradation. FEBS J 2016; 283:1701-19. [PMID: 26929175 DOI: 10.1111/febs.13696] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/09/2016] [Accepted: 02/25/2016] [Indexed: 11/27/2022]
Abstract
UNLABELLED The heteropolysaccharide xyloglucan (XyG) comprises up to one-quarter of the total carbohydrate content of terrestrial plant cell walls and, as such, represents a significant reservoir in the global carbon cycle. The complex composition of XyG requires a consortium of backbone-cleaving endo-xyloglucanases and side-chain cleaving exo-glycosidases for complete saccharification. The biochemical basis for XyG utilization by the model Gram-negative soil saprophytic bacterium Cellvibrio japonicus is incompletely understood, despite the recent characterization of associated side-chain cleaving exo-glycosidases. We present a detailed functional and structural characterization of a multimodular enzyme encoded by gene locus CJA_2477. The CJA_2477 gene product comprises an N-terminal glycoside hydrolase family 74 (GH74) endo-xyloglucanase module in train with two carbohydrate-binding modules (CBMs) from families 10 and 2 (CBM10 and CBM2). The GH74 catalytic domain generates Glc4 -based xylogluco-oligosaccharide (XyGO) substrates for downstream enzymes through an endo-dissociative mode of action. X-ray crystallography of the GH74 module, alone and in complex with XyGO products spanning the entire active site, revealed a broad substrate-binding cleft specifically adapted to XyG recognition, which is composed of two seven-bladed propeller domains characteristic of the GH74 family. The appended CBM10 and CBM2 members notably did not bind XyG, nor other soluble polysaccharides, and instead were specific cellulose-binding modules. Taken together, these data shed light on the first step of xyloglucan utilization by C. japonicus and expand the repertoire of GHs and CBMs for selective biomass analysis and utilization. DATABASE Structural data have been deposited in the RCSB protein database under the Protein Data Bank codes: 5FKR, 5FKS, 5FKT and 5FKQ.
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Affiliation(s)
- Mohamed Attia
- Michael Smith Laboratories and Department of Chemistry, University of British Columbia, Vancouver, Canada
| | | | | | - Harry Brumer
- Michael Smith Laboratories and Department of Chemistry, University of British Columbia, Vancouver, Canada
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Schiefner A, Angelov A, Liebl W, Skerra A. Structural basis for cellulose binding by the type A carbohydrate-binding module 64 of Spirochaeta thermophila. Proteins 2016; 84:855-8. [PMID: 26868291 DOI: 10.1002/prot.25010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Revised: 01/04/2016] [Accepted: 01/25/2016] [Indexed: 11/06/2022]
Abstract
Spirochaeta thermophila secretes seven glycoside hydrolases for plant biomass degradation that carry a carbohydrate-binding module 64 (CBM64) appended at the C-terminus. CBM64 adsorbs to various β1-4-linked pyranose substrates and shows high affinity for cellulose. We present the first crystal structure of a CBM64 at 1.2 Å resolution, which reveals a jelly-roll-like fold corresponding to a surface-binding type A CBM. Modeling of its interaction with cellulose indicates that CBM64 achieves association with the hydrophobic face of β-linked pyranose chains via a unique coplanar arrangement of four exposed tryptophan side chains. Proteins 2016; 84:855-858. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- André Schiefner
- Munich Center for Integrated Protein Science (CIPS-M) and Lehrstuhl für Biologische Chemie, Technische Universität München, 85354 Freising (Weihenstephan), Germany
| | - Angel Angelov
- Lehrstuhl Für Mikrobiologie, Technische Universität München, 85354 Freising (Weihenstephan), Germany
| | - Wolfgang Liebl
- Lehrstuhl Für Mikrobiologie, Technische Universität München, 85354 Freising (Weihenstephan), Germany
| | - Arne Skerra
- Munich Center for Integrated Protein Science (CIPS-M) and Lehrstuhl für Biologische Chemie, Technische Universität München, 85354 Freising (Weihenstephan), Germany
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Abstract
The enzyme-catalysed degradation of oligo and polysaccharides is of considerable interest in many fields ranging from the fundamental–understanding the intrinsic chemical beauty–through to the applied, including diverse practical applications in medicine and biotechnology. Carbohydrates are the most stereochemically-complex biopolymer, and myriad different natural polysaccharides have led to evolution of multifaceted enzyme consortia for their degradation. The glycosidic bonds that link sugar monomers are among the most chemically-stable, yet enzymatically-labile, bonds in the biosphere. That glycoside hydrolases can achieve a rate enhancement (kcat/kuncat) >1017-fold provides testament to their remarkable proficiency and the sophistication of their catalysis reaction mechanisms. The last two decades have seen significant advances in the discovery of new glycosidase sequences, sequence-based classification into families and clans, 3D structures and reaction mechanisms, providing new insights into enzymatic catalysis. New impetus to these studies has been provided by the challenges inherent in plant and microbial polysaccharide degradation, both in the context of environmentally-sustainable routes to foods and biofuels, and increasingly in human nutrition. Study of the reaction mechanism of glycoside hydrolases has also inspired the development of enzyme inhibitors, both as mechanistic probes and increasingly as therapeutic agents. We are on the cusp of a new era where we are learning how to dovetail powerful computational techniques with structural and kinetic data to provide an unprecedented view of conformational details of enzyme action.
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