| 1. |
- Bulone, Vincent, 1967-, et al.
(författare)
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Methods for manufacturing plant cell walls comprising chitin
- 2010
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Patent (populärvet., debatt m.m.)abstract
- Methods and means are provided for the modification of the reactivity of plant secondary cell walls, particularly in cotton cell walls found in cotton fibers. This can be conveniently achieved by expressing a chimeric gene encoding a Saprolegnia monoica chitin synthase in cotton plants.
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| 2. |
- Fugelstad, Johanna, et al.
(författare)
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Identification of the cellulose synthase genes from the Oomycete Saprolegnia monoica and effect of cellulose synthesis inhibitors on gene expression and enzyme activity
- 2009
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Ingår i: Fungal Genetics and Biology. - : Elsevier BV. - 1087-1845 .- 1096-0937. ; 46:10, s. 759-767
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose biosynthesis is a vital but yet poorly understood biochemical process in Oomycetes. Here, we report the identification and characterization of the cellulose synthase genes (CesA) from Saprolegnia monoica. Southern blot experiments revealed the occurrence of three CesA homologues in this species and phylogenetic analyses confirmed that Oomycete CesAs form a clade of their own. All gene products contained the D,D,D,QXXRW signature of most processive glycosyltransferases, including cellulose synthases. However, their N-terminal ends exhibited Oomycete-specific domains, i.e. Pleckstrin Homology domains, or conserved domains of an unknown function together with additional putative transmembrane domains. Mycelial growth was inhibited in the presence of the cellulose biosynthesis inhibitors 2,6-dichlorobenzonitrile or Congo Red. This inhibition was accompanied by a higher expression of all CesA genes in the mycelium and increased in vitro glucan synthase activities. Altogether, our data strongly suggest a direct involvement of the identified CesA genes in cellulose biosynthesis.
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| 3. |
- Guerriero, Gea, et al.
(författare)
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A WDR gene is a conserved member of a chitin synthase gene cluster and influences the cell wall in Aspergillus nidulans
- 2016
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Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 17:7, s. 1031-
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Tidskriftsartikel (refereegranskat)abstract
- WD40 repeat (WDR) proteins are pleiotropic molecular hubs. We identify a WDR gene that is a conserved genomic neighbor of a chitin synthase gene in Ascomycetes. The WDR gene is unique to fungi and plants, and was called Fungal Plant WD (FPWD). FPWD is within a cell wall metabolism gene cluster in the Ascomycetes (Pezizomycotina) comprising chsD, a Chs activator and a GH17 glucanase. The FPWD, AN1556.2 locus was deleted in Aspergillus nidulans strain SAA.111 by gene replacement and only heterokaryon transformants were obtained. The re-annotation of Aspergilli genomes shows that AN1556.2 consists of two tightly linked separate genes, i.e., the WDR gene and a putative beta-flanking gene of unknown function. The WDR and the beta-flanking genes are conserved genomic neighbors localized within a recently identified metabolic cell wall gene cluster in genomes of Aspergilli. The heterokaryons displayed increased susceptibility to drugs affecting the cell wall, and their phenotypes, observed by optical, confocal, scanning electron and atomic force microscopy, suggest cell wall alterations. Quantitative real-time PCR shows altered expression of some cell wall-related genes. The possible implications on cell wall biosynthesis are discussed.
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| 4. |
- Guerriero, Gea, et al.
(författare)
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Analysis of cellulose synthase genes from domesticated apple identifies collinear genes WDR53 and CesA8A : Partial co-expression, bicistronic mRNA, and alternative splicing of CESA8A
- 2012
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Ingår i: Journal of Experimental Botany. - : Oxford University Press. - 0022-0957 .- 1460-2431. ; 63:16, s. 6045-6056
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose synthase (CesA) genes constitute a complex multigene family with six major phylogenetic clades in angiosperms. The recently sequenced genome of domestic apple, Malus-domestica was mined for CesA genes, by blasting full-length cellulose synthase protein (CESA) sequences annotated in the apple genome against protein databases from the plant models Arabidopsis thaliana and Populus trichocarpa. Thirteen genes belonging to the six angiosperm CesA clades and coding for proteins with conserved residues typical of processive glycosyltransferases from family 2 were detected. Based on their phylogenetic relationship to Arabidopsis CESAs, as well as expression patterns, a nomenclature is proposed to facilitate further studies. Examination of their genomic organization revealed that MdCesA8-A is closely linked and co-oriented with WDR53, a gene coding for a WD40 repeat protein. The WDR53 and CesA8 genes display conserved collinearity in dicots and are partially co-expressed in the apple xylem. Interestingly, the presence of a bicistronic WDR53-CesA8A transcript was detected in phytoplasma-infected phloem tissues of apple. The bicistronic transcript contains a spliced intergenic sequence that is predicted to fold into hairpin structures typical of internal ribosome entry sites, suggesting its potential cap-independent translation. Surprisingly, the CesA8A cistron is alternatively spliced and lacks the zinc-binding domain. The possible roles of WDR53 and the alternatively spliced CESA8 variant during cellulose biosynthesis in M.-xdomestica are discussed.
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| 5. |
- Guerriero, Gea, et al.
(författare)
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Chitin Synthases from Saprolegnia Are Involved in Tip Growth and Represent a Potential Target for Anti-Oomycete Drugs
- 2010
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Ingår i: PLOS PATHOG. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 6:8, s. e1001070-
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Tidskriftsartikel (refereegranskat)abstract
- Oomycetes represent some of the most devastating plant and animal pathogens. Typical examples are Phytophthora infestans, which causes potato and tomato late blight, and Saprolegnia parasitica, responsible for fish diseases. Despite the economical and environmental importance of oomycete diseases, their control is difficult, particularly in the aquaculture industry. Carbohydrate synthases are vital for hyphal growth and represent interesting targets for tackling the pathogens. The existence of 2 different chitin synthase genes (SmChs1 and SmChs2) in Saprolegnia monoica was demonstrated using bioinformatics and molecular biology approaches. The function of SmCHS2 was unequivocally demonstrated by showing its catalytic activity in vitro after expression in Pichia pastoris. The recombinant SmCHS1 protein did not exhibit any activity in vitro, suggesting that it requires other partners or effectors to be active, or that it is involved in a different process than chitin biosynthesis. Both proteins contained N-terminal Microtubule Interacting and Trafficking domains, which have never been reported in any other known carbohydrate synthases. These domains are involved in protein recycling by endocytosis. Enzyme kinetics revealed that Saprolegnia chitin synthases are competitively inhibited by nikkomycin Z and quantitative PCR showed that their expression is higher in presence of the inhibitor. The use of nikkomycin Z combined with microscopy showed that chitin synthases are active essentially at the hyphal tips, which burst in the presence of the inhibitor, leading to cell death. S. parasitica was more sensitive to nikkomycin Z than S. monoica. In conclusion, chitin synthases with species-specific characteristics are involved in tip growth in Saprolegnia species and chitin is vital for the micro-organisms despite its very low abundance in the cell walls. Chitin is most likely synthesized transiently at the apex of the cells before cellulose, the major cell wall component in oomycetes. Our results provide important fundamental information on cell wall biogenesis in economically important species, and demonstrate the potential of targeting oomycete chitin synthases for disease control.
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| 6. |
- Guerriero, Gea, et al.
(författare)
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The RY/Sph element mediates transcriptional repression of maturation genes from late maturation to early seedling growth
- 2009
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 184:3, s. 552-565
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Tidskriftsartikel (refereegranskat)abstract
- P>In orthodox seeds, the transcriptional activator ABI3 regulates two major stages in embryo maturation: a mid-maturation (MAT) stage leading to accumulation of storage compounds, and a late maturation (LEA) stage leading to quiescence and desiccation tolerance. Our aim was to elucidate mechanisms for transcriptional shutdown of MAT genes during late maturation, to better understand phase transition between MAT and LEA stages. Using transgenic and transient approaches in Nicotiana, we examined activities of two ABI3-dependent reporter genes driven by multimeric RY and abscisic acid response elements (ABREs) from a Brassica napus napin gene, termed RY and ABRE, where the RY reporter requires ABI3 DNA binding. Expression of RY peaks during mid-maturation and drops during late maturation, mimicking the MAT gene program, and in Arabidopsis thaliana RY elements are over-represented in MAT, but not in LEA, genes. The ABI3 transactivation of RY is inhibited by staurosporine, by a PP2C phosphatase, and by a repressor of maturation genes, VAL1/HSI2. The RY element mediates repression of MAT genes, and we propose that transcriptional shutdown of the MAT program during late maturation involves inhibition of ABI3 DNA binding by dephosphorylation. Later, during seedling growth, VAL1/HSI2 family repressors silence MAT genes by binding RY elements. New Phytologist (2009)doi: 10.1111/j.1469-8137.2009.02977.x.
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| 7. |
- Guerriero, Gea, et al.
(författare)
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WD4O-Repeat Proteins in Plant Cell Wall Formation : Current Evidence and Research Prospects
- 2015
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Ingår i: Frontiers in Plant Science. - : FRONTIERS MEDIA. - 1664-462X. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The metabolic complexity of living organisms relies on supramolecular protein structures which ensure vital processes, such as signal transduction, transcription, translation and cell wall synthesis. In eukaryotes WD40-repeat (WDR) proteins often function as molecular "hubs" mediating supramolecular interactions. WDR proteins may display a variety of interacting partners and participate in the assembly of complexes involved in distinct cellular functions. In plants, the formation of lignocellulosic biomass involves extensive synthesis of cell wall polysaccharides, a process that requires the assembly of large transmembrane enzyme complexes, intensive vesicle trafficking, interactions with the cytoskeleton, and coordinated gene expression. Because of their function as supramolecular hubs, WDR proteins could participate in each or any of these steps, although to date only few WDR proteins have been linked to the cell wall by experimental evidence. Nevertheless, several potential cell wall-related WDR proteins were recently identified using in silico approaches, such as analyses of co-expression, interactome and conserved gene neighborhood. Notably, some WDR genes are frequently genomic neighbors of genes coding for GT2-family polysaccharide synthases in eukaryotes, and this WDR-GT2 collinear microsynteny is detected in diverse taxa. In angiosperms, two WDR genes are collinear to cellulose synthase genes, CesAs, whereas in ascomycetous fungi several WDR genes are adjacent to chitin synthase genes, chs. In this Perspective we summarize and discuss experimental and in silico studies on the possible involvement of WDR proteins in plant cell wall formation. The prospects of biotechnological engineering for enhanced biomass production are discussed.
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| 8. |
- Guerriero, Gea, et al.
(författare)
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What Do We Really Know about Cellulose Biosynthesis in Higher Plants?
- 2010
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Ingår i: JOURNAL OF INTEGRATIVE PLANT BIOLOGY. - : Wiley. - 1672-9072 .- 1744-7909. ; 52:2, s. 161-175
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Forskningsöversikt (refereegranskat)abstract
- Cellulose biosynthesis is one of the most important biochemical processes in plant biology. Despite the considerable progress made during the last decade, numerous fundamental questions related to this key process in plant development are outstanding. Numerous models have been proposed through the years to explain the detailed molecular events of cellulose biosynthesis. Almost all models integrate solid experimental data with hypotheses on several of the steps involved in the process. Speculative models are most useful to stimulate further research investigations and bring new exciting ideas to the field. However, it is important to keep their hypothetical nature in mind and be aware of the risk that some undemonstrated hypotheses may progressively become admitted. In this review, we discuss the different steps required for cellulose formation and crystallization, and highlight the most important specific aspects that are supported by solid experimental data.
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| 9. |
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| 10. |
- Rajangam, Alex S., et al.
(författare)
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MAP20, a Microtubule-Associated Protein in the Secondary Cell Walls of Hybrid Aspen, Is a Target of the Cellulose Synthesis Inhibitor 2,6-Dichlorobenzonitrile
- 2008
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 148:3, s. 1283-1294
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Tidskriftsartikel (refereegranskat)abstract
- We have identified a gene, denoted PttMAP20, which is strongly up-regulated during secondary cell wall synthesis and tightly coregulated with the secondary wall-associated CESA genes in hybrid aspen (Populus tremula x tremuloides). Immunolocalization studies with affinity-purified antibodies specific for PttMAP20 revealed that the protein is found in all cell types in developing xylem and that it is most abundant in cells forming secondary cell walls. This PttMAP20 protein sequence contains a highly conserved TPX2 domain first identified in a microtubule-associated protein (MAP) in Xenopus laevis. Overexpression of PttMAP20 in Arabidopsis (Arabidopsis thaliana) leads to helical twisting of epidermal cells, frequently associated with MAPs. In addition, a PttMAP20-yellow fluorescent protein fusion protein expressed in tobacco (Nicotiana tabacum) leaves localizes to microtubules in leaf epidermal pavement cells. Recombinant PttMAP20 expressed in Escherichia coli also binds specifically to in vitro-assembled, taxol-stabilized bovine microtubules. Finally, the herbicide 2,6-dichlorobenzonitrile, which inhibits cellulose synthesis in plants, was found to bind specifically to PttMAP20. Together with the known function of cortical microtubules in orienting cellulose microfibrils, these observations suggest that PttMAP20 has a role in cellulose biosynthesis.
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| 11. |
- Siddiqui, K. S., et al.
(författare)
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A chemically modified α-amylase with a molten-globule state has entropically driven enhanced thermal stability
- 2010
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Ingår i: Protein Engineering Design & Selection. - : Oxford University Press (OUP). - 1741-0126 .- 1741-0134. ; 23:10, s. 769-780
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Tidskriftsartikel (refereegranskat)abstract
- The thermostability properties of TAA were investigated by chemically modifying carboxyl groups on the surface of the enzyme with AMEs. The TAAMOD exhibited a 200 improvement in starch-hydrolyzing productivity at 60°C. By studying the kinetic, thermodynamic and biophysical properties, we found that TAAMOD had formed a thermostable, MG state, in which the unfolding of the tertiary structure preceded that of the secondary structure by at least 20°C. The X-ray crystal structure of TAAMOD revealed no new permanent interactions (electrostatic or other) resulting from the modification. By deriving thermodynamic activation parameters of TAAMOD, we rationalised that thermostabilisation have been caused by a decrease in the entropy of the transition state, rather than being enthalpically driven. Far-UV CD shows that the origin of decreased entropy may have arisen from a higher helical content of TAAMOD. This study provides new insight into the intriguing properties of an MG state resulting from the chemical modification of TAA.
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| 12. |
- Winzell, Anders, et al.
(författare)
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Biochemical characterization of family 43 glycosyltransferases in the Populus xylem : challenges and prospects
- 2010
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Ingår i: Plant Biotechnology. - : Japanese Society for Plant Cell and Molecular Biology. - 1342-4580 .- 1347-6114. ; 27:3, s. 283-288
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Tidskriftsartikel (refereegranskat)abstract
- Wood formation is a biological process of great economical importance. Genes active during the secondary cellwall formation of wood fibers from Populus tremulatremuloides were previously identified by expression profilingthrough microarray analyses. A number of these genes encode glycosyltransferases (GTs) with unknown substratespecificities. Here we report heterologous expression of one of these enzymes, PttGT43A, a putative IRREGULARXYLEM9 (IRX9) homologue. Expression trials in Pichia pastoris and insect cells revealed very low levels of accumulationof immunoreactive PttGT43A, whereas transient expression in Nicotiana benthamiana leaves by Agrobacterium infiltration(agroinfiltration) using a viral vector produced substantial amounts of protein that mostly precipitated in the crude pellet.Agroinfiltration induced weak endogenous xylosyltransferase activity in microsomal extracts, and transient PttGT43Aexpression further increased this activity, albeit only to low levels. PttGT43A may be inactive as an individual subunit,requiring complex formation with unknown partners to display enzymatic activity. Our results suggest that transient coexpressionin leaves of candidate subunit GTs may provide a viable approach for formation of an active xylanxylosyltransferase enzymatic complex.
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