The class VIII myosin ATM2 stabilizes actin-plasma membrane contacts in tobacco pollen tubes by locally promoting PtdIns(4,5)P₂ formation.
4 affiliations
- 1Department of Plant Biochemistry, Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
- 2Department of Biophysical Chemistry, Institute of Chemistry, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany.
- 3Department of Experimental Plant Biology, Faculty of Science, Charles University, Prague, Czech Republic.
- 4Department of Plant Biochemistry, Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany. [email protected].
Abstract
The intersection of actin filaments with the plasma membrane (PM) in plant cells involves lipid-protein interactions by the Arabidopsis class VIII myosin ATM2 that are currently not understood. Using pollen tube cells as a model, we describe how ATM2 enables actin-PM contacts by modulating membrane lipid nano-organization. ATM2 bound anionic PM lipids, including phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P₂), with no apparent preference for any particular lipid species. Overexpression of ATM2 unexpectedly stabilized actin dynamics and altered pollen tube morphology. Actin dynamics remained unaltered upon overexpression of a lipid-binding-defective ATM2 variant. ATM2 effects on actin dynamics required PtdIns(4,5)P₂, as artificial PtdIns(4,5)P₂ depletion in pollen tubes abolished the effects of full-length ATM2 on actin dynamics despite its retained PM association. ATM2 colocalized and interacted with the PI4P 5-kinase PIP5K2, which resides at actin-PM contacts and forms PtdIns(4,5)P₂ nanodomains facilitating rho-of-plants-dependent actin stabilization. Upon ATM2 overexpression, a fluorescent PtdIns(4,5)P₂ biosensor decorated an extended PM region in vivo, indicating a promoting effect of ATM2 on PtdIns(4,5)P₂ abundance. The catalytic activity of purified recombinant PIP5K2 protein was enhanced upon coincubation with a purified carboxy-terminal ATM2 fragment in vitro, suggesting that ATM2 contributes to the intrinsic regulation of PtdIns(4,5)P₂ formation. Actin dynamics are thus stabilized at the actin-PM interface by ATM2 locally promoting the formation of PtdIns(4,5)P₂ nanodomains, thereby self-reinforcing ATM2 recruitment while also facilitating rho of plants activation to stabilize membrane-proximal actin filaments.
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BibTeX
@article{wagner2026class,
title = {{The class VIII myosin ATM2 stabilizes actin-plasma membrane contacts in tobacco pollen tubes by locally promoting PtdIns(4,5)P₂ formation.}},
author = {Vera C Wagner and Marta Fratini and Johanna Uhlenberg and Alexandra Schutkowski and Gottfried Hamm and Christoph Kastner and Kirsten Bacia and Kateřina Schwarzerová and Ingo Heilmann},
journal = {Nature plants},
year = {2026},
month = oct,
doi = {10.1038/s41477-026-02427-0},
url = {https://europepmc.org/article/MED/42888236},
note = {CC BY},
}
RIS
TY - JOUR
TI - The class VIII myosin ATM2 stabilizes actin-plasma membrane contacts in tobacco pollen tubes by locally promoting PtdIns(4,5)P₂ formation.
AU - Vera C Wagner
AU - Marta Fratini
AU - Johanna Uhlenberg
AU - Alexandra Schutkowski
AU - Gottfried Hamm
AU - Christoph Kastner
AU - Kirsten Bacia
AU - Kateřina Schwarzerová
AU - Ingo Heilmann
PY - 2026
DA - 2026/10/16
JO - Nature plants
DO - 10.1038/s41477-026-02427-0
UR - https://europepmc.org/article/MED/42888236
AB - The intersection of actin filaments with the plasma membrane (PM) in plant cells involves lipid-protein interactions by the Arabidopsis class VIII myosin ATM2 that are currently not understood. Using pollen tube cells as a model, we describe how ATM2 enables actin-PM contacts by modulating membrane lipid nano-organization. ATM2 bound anionic PM lipids, including phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P₂), with no apparent preference for any particular lipid species. Overexpression of ATM2 unexpectedly stabilized actin dynamics and altered pollen tube morphology. Actin dynamics remained unaltered upon overexpression of a lipid-binding-defective ATM2 variant. ATM2 effects on actin dynamics required PtdIns(4,5)P₂, as artificial PtdIns(4,5)P₂ depletion in pollen tubes abolished the effects of full-length ATM2 on actin dynamics despite its retained PM association. ATM2 colocalized and interacted with the PI4P 5-kinase PIP5K2, which resides at actin-PM contacts and forms PtdIns(4,5)P₂ nanodomains facilitating rho-of-plants-dependent actin stabilization. Upon ATM2 overexpression, a fluorescent PtdIns(4,5)P₂ biosensor decorated an extended PM region in vivo, indicating a promoting effect of ATM2 on PtdIns(4,5)P₂ abundance. The catalytic activity of purified recombinant PIP5K2 protein was enhanced upon coincubation with a purified carboxy-terminal ATM2 fragment in vitro, suggesting that ATM2 contributes to the intrinsic regulation of PtdIns(4,5)P₂ formation. Actin dynamics are thus stabilized at the actin-PM interface by ATM2 locally promoting the formation of PtdIns(4,5)P₂ nanodomains, thereby self-reinforcing ATM2 recruitment while also facilitating rho of plants activation to stabilize membrane-proximal actin filaments.
SN - 2055-0278
ER -