Targeting of plasmodesmal proteins requires unconventional signals
Date
2023-08-02
Journal Title
Journal ISSN
Volume Title
Publisher
The Plant Cell
Abstract
Effective cellular signaling relies on precise spatial localization and dynamic interactions among proteins in specific subcellular compartments or niches, such as cell-to-cell contact sites and junctions. In plants, endogenous and pathogenic proteins gained the ability to target plasmodesmata, membrane-lined cytoplasmic connections, through evolution to regulate or exploit cellular signaling across cell wall boundaries. For example, the receptor-like membrane protein PLASMODESMATA-LOCATED PROTEIN 5 (PDLP5), a potent regulator of plasmodesmal permeability, generates feed-forward or feed-back signals important for plant immunity and root development. However, the molecular features that determine the plasmodesmal association of PDLP5 or other proteins remain largely unknown, and no protein motifs have been identified as plasmodesmal targeting signals. Here, we developed an approach combining custom-built machine-learning algorithms and targeted mutagenesis to examine PDLP5 in Arabidopsis thaliana and Nicotiana benthamiana. We report that PDLP5 and its closely related proteins carry unconventional targeting signals consisting of short stretches of amino acids. PDLP5 contains 2 divergent, tandemly arranged signals, either of which is sufficient for localization and biological function in regulating viral movement through plasmodesmata. Notably, plasmodesmal targeting signals exhibit little sequence conservation but are located similarly proximal to the membrane. These features appear to be a common theme in plasmodesmal targeting.
Description
This article was originally published in The Plant Cell. The version of record is available at: https://doi.org/10.1093/plcell/koad152. © The Author(s) 2023. Published by Oxford University Press on behalf of American Society of Plant Biologists.
Keywords
Citation
Gabriel Robles Luna, Jiefu Li, Xu Wang, Li Liao, Jung-Youn Lee, Targeting of plasmodesmal proteins requires unconventional signals, The Plant Cell, Volume 35, Issue 8, August 2023, Pages 3035–3052, https://doi.org/10.1093/plcell/koad152