Glycosylphosphatidylinositol (GPI) Modification Serves as a Primary Plasmodesmal Sorting Signal.

Published

Journal Article

Plasmodesmata (Pd) are membranous channels that serve as a major conduit for cell-to-cell communication in plants. The Pd-associated β-1,3-glucanase (BG_pap) and CALLOSE BINDING PROTEIN1 (PDCB1) were identified as key regulators of Pd conductivity. Both are predicted glycosylphosphatidylinositol-anchored proteins (GPI-APs) carrying a conserved GPI modification signal. However, the subcellular targeting mechanism of these proteins is unknown, particularly in the context of other GPI-APs not associated with Pd Here, we conducted a comparative analysis of the subcellular targeting of the two Pd-resident and two unrelated non-Pd GPI-APs in Arabidopsis (Arabidopsis thaliana). We show that GPI modification is necessary and sufficient for delivering both BG_pap and PDCB1 to Pd Moreover, the GPI modification signal from both Pd- and non-Pd GPI-APs is able to target a reporter protein to Pd, likely to plasma membrane microdomains enriched at Pd As such, the GPI modification serves as a primary Pd sorting signal in plant cells. Interestingly, the ectodomain, a region that carries the functional domain in GPI-APs, in Pd-resident proteins further enhances Pd accumulation. However, in non-Pd GPI-APs, the ectodomain overrides the Pd targeting function of the GPI signal and determines a specific GPI-dependent non-Pd localization of these proteins at the plasma membrane and cell wall. Domain-swap analysis showed that the non-Pd localization is also dominant over the Pd-enhancing function mediated by a Pd ectodomain. In conclusion, our results indicate that segregation between Pd- and non-Pd GPI-APs occurs prior to Pd targeting, providing, to our knowledge, the first evidence of the mechanism of GPI-AP sorting in plants.

Full Text

Duke Authors

Cited Authors

  • Zavaliev, R; Dong, X; Epel, BL

Published Date

  • October 2016

Published In

Volume / Issue

  • 172 / 2

Start / End Page

  • 1061 - 1073

PubMed ID

  • 27559035

Pubmed Central ID

  • 27559035

Electronic International Standard Serial Number (EISSN)

  • 1532-2548

International Standard Serial Number (ISSN)

  • 0032-0889

Digital Object Identifier (DOI)

  • 10.1104/pp.16.01026

Language

  • eng