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Hoffmann N, McFarlane HE. Xyloglucan side chains enable polysaccharide secretion to the plant cell wall. Dev Cell 2024:S1534-5807(24)00384-8. [PMID: 38971156 DOI: 10.1016/j.devcel.2024.06.006] [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: 12/13/2023] [Revised: 04/16/2024] [Accepted: 06/08/2024] [Indexed: 07/08/2024]
Abstract
Plant cell walls are essential for growth. The cell wall hemicellulose xyloglucan (XyG) is produced in the Golgi apparatus before secretion. Loss of the Arabidopsis galactosyltransferase MURUS3 (MUR3) decreases XyG d-galactose side chains and causes intracellular aggregations and dwarfism. It is unknown how changing XyG synthesis can broadly impact organelle organization and growth. We show that intracellular aggregations are not unique to mur3 and are found in multiple mutant lines with reduced XyG D-galactose side chains. mur3 aggregations disrupt subcellular trafficking and induce formation of intracellular cell-wall-like fragments. Addition of d-galacturonic acid onto XyG can restore growth and prevent mur3 aggregations. These results indicate that the presence, but not the composition, of XyG side chains is essential, likely by ensuring XyG solubility. Our results suggest that XyG polysaccharides are synthesized in a highly substituted form for efficient secretion and then later modified by cell-wall-localized enzymes to fine-tune cell wall properties.
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Affiliation(s)
- Natalie Hoffmann
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada
| | - Heather E McFarlane
- Department of Cell & Systems Biology, University of Toronto, Toronto, ON M5S 3B2, Canada.
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Liu MCJ, Yeh FLJ, Yvon R, Simpson K, Jordan S, Chambers J, Wu HM, Cheung AY. Extracellular pectin-RALF phase separation mediates FERONIA global signaling function. Cell 2024; 187:312-330.e22. [PMID: 38157854 DOI: 10.1016/j.cell.2023.11.038] [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: 05/23/2023] [Revised: 10/01/2023] [Accepted: 11/29/2023] [Indexed: 01/03/2024]
Abstract
The FERONIA (FER)-LLG1 co-receptor and its peptide ligand RALF regulate myriad processes for plant growth and survival. Focusing on signal-induced cell surface responses, we discovered that intrinsically disordered RALF triggers clustering and endocytosis of its cognate receptors and FER- and LLG1-dependent endocytosis of non-cognate regulators of diverse processes, thus capable of broadly impacting downstream responses. RALF, however, remains extracellular. We demonstrate that RALF binds the cell wall polysaccharide pectin. They phase separate and recruit FER and LLG1 into pectin-RALF-FER-LLG1 condensates to initiate RALF-triggered cell surface responses. We show further that two frequently encountered environmental challenges, elevated salt and temperature, trigger RALF-pectin phase separation, promiscuous receptor clustering and massive endocytosis, and that this process is crucial for recovery from stress-induced growth attenuation. Our results support that RALF-pectin phase separation mediates an exoskeletal mechanism to broadly activate FER-LLG1-dependent cell surface responses to mediate the global role of FER in plant growth and survival.
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Affiliation(s)
- Ming-Che James Liu
- Department of Biochemistry and Molecular Biology, University of Massachusetts, 710 N. Pleasant St., Lederle Graduate Tower, Amherst, MA 01003, USA
| | - Fang-Ling Jessica Yeh
- Department of Biochemistry and Molecular Biology, University of Massachusetts, 710 N. Pleasant St., Lederle Graduate Tower, Amherst, MA 01003, USA; Plant Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA
| | - Robert Yvon
- Department of Biochemistry and Molecular Biology, University of Massachusetts, 710 N. Pleasant St., Lederle Graduate Tower, Amherst, MA 01003, USA; Molecular and Cell Biology Program, University of Massachusetts, Amherst, MA 01003, USA
| | - Kelly Simpson
- Department of Biochemistry and Molecular Biology, University of Massachusetts, 710 N. Pleasant St., Lederle Graduate Tower, Amherst, MA 01003, USA; Molecular and Cell Biology Program, University of Massachusetts, Amherst, MA 01003, USA
| | - Samuel Jordan
- Department of Biochemistry and Molecular Biology, University of Massachusetts, 710 N. Pleasant St., Lederle Graduate Tower, Amherst, MA 01003, USA
| | - James Chambers
- Light Microscopy Core Facility, Institute of Applied Life Sciences, University of Massachusetts, Amherst, MA 01003, USA
| | - Hen-Ming Wu
- Department of Biochemistry and Molecular Biology, University of Massachusetts, 710 N. Pleasant St., Lederle Graduate Tower, Amherst, MA 01003, USA; Molecular and Cell Biology Program, University of Massachusetts, Amherst, MA 01003, USA.
| | - Alice Y Cheung
- Department of Biochemistry and Molecular Biology, University of Massachusetts, 710 N. Pleasant St., Lederle Graduate Tower, Amherst, MA 01003, USA; Molecular and Cell Biology Program, University of Massachusetts, Amherst, MA 01003, USA; Plant Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA.
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