Comparative Structural and Computational Analysis Supports Eighteen Cellulose Synthases in the Plant Cellulose Synthesis Complex

Nixon, B. Tracy; Mansouri, Katayoun; Singh, Abhishek; Du, Juan; Davis, Jonathan K.; Lee, Jung Goo; Slabaugh, Erin; Vandavasi, Venu Gopal; O’Neill, Hugh; Roberts, Eric M.; Roberts, Alison W.; Yingling, Yaroslava G.; Haigler, Candace H.

doi:10.1038/srep28696

Cited by 168 publications

(144 citation statements)

References 58 publications

(98 reference statements)

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“…1). These data are in agreement with recent freeze fracture transmission electron microscopy analyses that argue for a six-fold trimeric CesA assembly [41]. Nevertheless, it will be important to verify these estimates by directly observing the number of CesA subunits in the complex.…”

supporting

confidence: 79%

Cellulose and callose synthesis and organization in focus, what's new?

Schneider

Hanak

Persson

et al. 2016

Current Opinion in Plant Biology

102

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Article available under the terms of the CC-BY-NC-ND licence (https://creativecommons.org/licenses/by-nc-nd/4.0/) eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Abstract Plant growth and development are supported by plastic but strong cell walls. These walls consist largely of polysaccharides that vary in content and structure. Most of the polysaccharides are produced in the Golgi apparatus and are then secreted to the apoplast and built into the growing walls. However, the two glucan polymers cellulose and callose are synthesized at the plasma membrane by cellulose or callose synthase complexes, respectively. Cellulose is the most common cell wall polymer in land plants and provides strength to the walls to support directed cell expansion. In contrast, callose is integral to specialized cell walls, such as the cell plate that separates dividing cells and growing pollen tube walls, and maintains important functions during abiotic and biotic stress responses. The last years have seen a dramatic increase in our understanding of how cellulose and callose are manufactured, and new factors that regulate the synthases have been identified. Much of this knowledge has been amassed via various microscopy-based techniques, including various confocal techniques and super-resolution imaging. Here, we summarize and synthesize recent findings in the fields of cellulose and callose synthesis in plant biology. Title

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supporting

confidence: 79%

Cellulose and callose synthesis and organization in focus, what's new?

Schneider

Hanak

Persson

et al. 2016

Current Opinion in Plant Biology

102

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“…The width of the fibril-attached particle is consistent with size estimates for plant CesA oligomers, referred to as "rosettes," observed by freeze-fracture EM (11,29,30). CesA rosettes have recently been interpreted as hexamers of CesA trimers, yielding a total of 18 CesA molecules per complex and, accordingly, a maximum of 18 glucan chains per cellulose microfibril (31,32).…”

Section: Pttcesa8's N-terminal Cytosolic Domain Is Dispensable For Casupporting

confidence: 53%

A single heterologously expressed plant cellulose synthase isoform is sufficient for cellulose microfibril formation in vitro

Purushotham

Cho

Díaz-Moreno

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Plant cell walls are a composite material of polysaccharides, proteins, and other noncarbohydrate polymers. In the majority of plant tissues, the most abundant polysaccharide is cellulose, a linear polymer of glucose molecules. As the load-bearing component of the cell wall, individual cellulose chains are frequently bundled into micro and macrofibrils and are wrapped around the cell. Cellulose is synthesized by membrane-integrated and processive glycosyltransferases that polymerize UDP-activated glucose and secrete the nascent polymer through a channel formed by their own transmembrane regions. Plants express several different cellulose synthase isoforms during primary and secondary cell wall formation; however, so far, none has been functionally reconstituted in vitro for detailed biochemical analyses. Here we report the heterologous expression, purification, and functional reconstitution of Populus tremula x tremuloides CesA8 (PttCesA8), implicated in secondary cell wall formation. The recombinant enzyme polymerizes UDP-activated glucose to cellulose, as determined by enzyme degradation, permethylation glycosyl linkage analysis, electron microscopy, and mutagenesis studies. Catalytic activity is dependent on the presence of a lipid bilayer environment and divalent manganese cations. Further, electron microscopy analyses reveal that PttCesA8 produces cellulose fibers several micrometers long that occasionally are capped by globular particles, likely representing PttCesA8 complexes. Deletion of the enzyme's N-terminal RING-finger domain almost completely abolishes fiber formation but not cellulose biosynthetic activity. Our results demonstrate that reconstituted PttCesA8 is not only sufficient for cellulose biosynthesis in vitro but also suffices to bundle individual glucan chains into cellulose microfibrils.biopolymer | cellulose | glycosyltransferase | plant cell wall | membrane transport

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“…It is believed that the synthesis of glucan chains by the CESAs propels the complex through the PM, depositing cellulose microfibrils in its wake (McFarlane et al, 2014). The estimated size of cellulose microfibrils suggests that they are produced by CESA rosettes containing a total of 18 CESA proteins, which was validated in the moss Physcomitrella patens using an improved method for electron microscopy (Nixon et al, 2016). FP-tagged CESA enzymes also have been visualized in the PM of living cells from the model plant Arabidopsis (Arabidopsis thaliana; Paredez et al, 2006).…”

Section: Monitoring Cellulose Structure With Molecular Probesmentioning

confidence: 99%