Attention:The NSF Public Access Repository (PAR) system and access will be unavailable from 5:00 PM ET until 8:00 PM ET on Friday, September 11 due to maintenance. We apologize for the inconvenience.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: The TRAPPIII subunit, Trs85, has a dual role in the trafficking of cellulose synthase complexes in Arabidopsis
SUMMARY Plant cell walls are essential for defining plant growth and development, providing structural support to the main body and responding to abiotic and biotic cues. Cellulose, the main structural polymer of plant cell walls, is synthesized at the plasma membrane by cellulose synthase complexes (CSCs). The construction and transport of CSCs to and from the plasma membrane is poorly understood but is known to rely on the coordinated activity of cellulose synthase‐interactive protein 1 (CSI1), a key regulator of CSC trafficking. In this study, we found that Trs85, a TRAPPIII complex subunit, interacted with CSI1in vitro. Using functional genetics and live‐cell imaging, we have shown thattrs85‐1mutants have reduced cellulose content, stimulated CSC delivery, an increased population of static CSCs and deficient clathrin‐mediated endocytosis in the primary cell wall. Overall, our findings suggest that Trs85 has a dual role in the trafficking of CSCs, by negatively regulating the exocytosis and clathrin‐mediated endocytosis of CSCs.  more » « less
Award ID(s):
1951007
PAR ID:
10569665
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Wiley
Date Published:
Journal Name:
The Plant Journal
Volume:
118
Issue:
5
ISSN:
0960-7412
Page Range / eLocation ID:
1475 to 1485
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; (, bioRxiv)
    Abstract The coupling of exo- and endocytic trafficking of Cellulose Synthase Complexes (CSCs) has been proposed to be important for maintaining the population of active CSCs at the plasma membrane (PM) and thus appropriate levels of cell wall assembly. Although actin and myosin are known to participate in the late stages of exocytosis of CSCs, their exact role during CSC internalization events remains controversial. We constructed a functional, photoconvertible fluorescent mEOS2-CESA6 reporter and developed single-particle live-cell imaging approaches to visualize and quantify the dynamic behavior of CSCs at the PM during internalization. Using the small molecule inhibitor of clathrin, Endosidin 9-17 or ES9-17, we confirmed that clathrin-mediated endocytosis is a major pathway for CSC internalization. We also found that the actin cytoskeleton is involved in CSC internalization. Genetic or chemical inhibition of actin, myosin, or the Arp2/3 complex significantly reduced the frequency of CSC internalization events and prolonged the CSC pause time prior to internalization. Additionally, we found that the Arp2/3 complex contributes to the late stage of exocytosis of CSCs into the PM. These results reveal a role for actomyosin and the Arp2/3 complex in both CSC secretion as well as internalization that was previously undescribed in plant cells. One sentence summaryDirect visualization of individual CSC internalization events reveals that actomyosin participates in CSC internalization and the Arp2/3 complex contributes to both exocytosis and internalization of CSCs through regulating the dynamic homeostasis of the cortical actin cytoskeleton. 
    more » « less
  2. ; ; ; ; (, The Plant Cell)
    Cellulose, the main component of the plant cell wall, is synthesized by the multimeric cellulose synthase (CESA) complex (CSC). In plant cells, CSCs are assembled in the endoplasmic reticulum or Golgi and transported through the endomembrane system to the plasma membrane (PM). However, how CESA catalytic activity or conserved motifs around the catalytic core influence vesicle trafficking or protein dynamics is not well understood. Here, we used yellow fluorescent protein (YFP)-tagged AtCESA6 and created 18 mutants in key motifs of the catalytic domain to analyze how they affected seedling growth, cellulose biosynthesis, complex formation, and CSC dynamics and trafficking in Arabidopsis thaliana. Seedling growth and cellulose content were reduced by nearly all mutations. Moreover, mutations in most conserved motifs slowed CSC movement in the PM as well as delivery of CSCs to the PM. Interestingly, mutations in the DDG and QXXRW motifs affected YFP-CESA6 abundance in the Golgi. These mutations also perturbed post-Golgi trafficking of CSCs. The 18 mutations were divided into 2 groups based on their phenotypes; we propose that Group I mutations cause CSC trafficking defects, whereas Group II mutations, especially in the QXXRW motif, affect protein folding and/or CSC rosette formation. Collectively, our results demonstrate that the CESA6 catalytic domain is essential for cellulose biosynthesis as well as CSC formation, protein folding and dynamics, and vesicle trafficking. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; ; et al (, Proceedings of the National Academy of Sciences)
    Cellulose, a primary component of plant cell walls, is synthesized by cellulose synthase complexes (CSCs) at the plasma membrane. Targeting this process with cellulose biosynthesis inhibitors (CBIs) has significantly advanced our understanding of plant cell wall formation and provided valuable compounds for herbicide development. Here, we identified a fungal natural product, 8-methyldichlorodiaporthin (MDD), as a broad-spectrum plant CBI. Structure–activity relationship analyses demonstrate that methylation modifications on the isocoumarin ring and chlorination of the side chain are crucial for MDD-induced growth inhibition. A chemical forward genetic screen inArabidopsis thalianarevealed two semidominant CESA1 mutations, causing A903T and H1024Y substitutions, that confer insensitivity to MDD. Both mutations locate to transmembrane domains of CESA1, and we show that MDD depletes CSCs from the plasma membrane and reduces cellulose content. Further genetic analyses indicate that thecesa1mddi1-1A903Tmutant also confers resistance to CBIs quinoxyphen and C17, but not to CBIs isoxaben, indaziflam, or ES20. Stacking additional point mutations conferring resistance to other CBIs,cesa3ixr1-1G998D, andcesa6es20-r3G935Einto thecesa1mddi1-1A903Tbackground yields multiple-drug-resistant lines that maintain normal growth. These findings establish MDD, as a natural CBI that likely targets CESA1, thereby extending our understanding of CSC regulation and abilities to develop multidrug-resistant crop varieties. These findings offer unique perspectives for weed management and plant biotechnology. 
    more » « less
  4. ; ; ; (, Glycobiology)
    Cellulose is an abundant component of plant cell wall matrices, and this para-crystalline polysaccharide is synthesized at the plasma membrane by motile Cellulose Synthase Complexes (CSCs). However, the factors that control CSC activity and motility are not fully resolved. In a targeted chemical screen, we identified the alkylated nojirimycin analog N-Dodecyl Deoxynojirimycin (ND-DNJ) as a small molecule that severely impacts Arabidopsis seedling growth. Previous work suggests that ND-DNJ-related compounds inhibit the biosynthesis of glucosylceramides (GlcCers), a class of glycosphingolipid associated with plant membranes. Our work uncovered major changes in the sphingolipidome of plants treated with ND-DNJ, including reductions in GlcCer abundance and altered acyl chain length distributions. Crystalline cellulose content was also reduced in ND-DNJ-treated plants as well as plants treated with the known GlcCer biosynthesis inhibitor N-[2-hydroxy-1-(4-morpholinylmethyl)-2-phenyl ethyl]-decanamide (PDMP) or plants containing a genetic disruption in GLUCOSYLCERAMIDE SYNTHASE (GCS), the enzyme responsible for sphingolipid glucosylation that results in GlcCer synthesis. Live-cell imaging revealed that CSC speed distributions were reduced upon treatment with ND-DNJ or PDMP, further suggesting an important relationship between glycosylated sphingolipid composition and CSC motility across the plasma membrane. These results indicate that multiple interventions compromising GlcCer biosynthesis disrupt cellulose deposition and CSC motility, suggesting that GlcCers regulate cellulose biosynthesis in plants. 
    more » « less
  5. ; ; ; ; ; ; (, New Phytologist)
    Summary Cellulose is an essential component of plant cell walls and an economically important source of food, paper, textiles, and biofuel. Despite its economic and biological significance, the regulation of cellulose biosynthesis is poorly understood. Phosphorylation and dephosphorylation of cellulose synthases (CESAs) were shown to impact the direction and velocity of cellulose synthase complexes (CSCs). However, the protein kinases that phosphorylate CESAs are largely unknown. We conducted research inArabidopsis thalianato reveal protein kinases that phosphorylate CESAs.In this study, we used yeast two‐hybrid, protein biochemistry, genetics, and live‐cell imaging to reveal the role of calcium‐dependent protein kinase32 (CPK32) in the regulation of cellulose biosynthesis inA. thaliana.We identified CPK32 using CESA3 as a bait in a yeast two‐hybrid assay. We showed that CPK32 phosphorylates CESA3 while it interacts with both CESA1 and CESA3. Overexpressing functionally defective CPK32 variant and phospho‐dead mutation of CESA3 led to decreased motility of CSCs and reduced crystalline cellulose content in etiolated seedlings. Deregulation of CPKs impacted the stability of CSCs.We uncovered a new function of CPKs that regulates cellulose biosynthesis and a novel mechanism by which phosphorylation regulates the stability of CSCs. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email