The class VIII myosin ATM2 stabilizes actin-plasma membrane contacts by locally promoting PtdIns(4,5)P2 nanodomain formation in tobacco pollen tubes

The class VIII myosin ATM2 stabilizes actin-plasma membrane contacts by locally promoting PtdIns(4,5)P2 nanodomain formation in tobacco pollen tubes | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article The class VIII myosin ATM2 stabilizes actin-plasma membrane contacts by locally promoting PtdIns(4,5)P 2 nanodomain formation in tobacco pollen tubes Ingo Heilmann, Vera Wagner, Marta Fratini, Johanna Uhlenberg, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7598484/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract The intersection of actin-filaments with the plasma membrane 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-plasma membrane contacts by modulating membrane lipid nano-organization. ATM2 binds both actin and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2), a lipid required for ATM2-plasma membrane-attachment. 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 effects of full-length ATM2 on actin dynamics despite its retained plasma membrane-association. ATM2 colocalized and interacted with the PI4P 5-kinase, PIP5K2, which resides at actin-plasma membrane-contacts and forms PtdIns(4,5)P2-nanodomains facilitating ROP-dependent actin-stabilization. Upon ATM2-overexpression, a fluorescent PtdIns(4,5)P2-biosensor decorated an expanded plasma membrane-region in vivo, indicating a promoting effect of ATM2 on PtdIns(4,5)P2-abundance. Moreover, catalytic activity of purified recombinant PIP5K2 protein was enhanced upon coincubation with a purified C-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-plasma membrane interface by ATM2 locally promoting the formation of PtdIns(4,5)P2-nanodomains, thereby self-reinforcing ATM2-recruitment while also facilitating ROP-activation to stabilize membrane-proximal actin-filaments. Biological sciences/Cell biology/Cell signalling/Lipid signalling Biological sciences/Cell biology/Cell signalling/Phosphoinositol signalling Actin-dynamics Actin-membrane interface PIP5K2 Membrane-nanostructure PIP2 Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7598484","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":524263411,"identity":"e56a4831-7553-4af2-90c5-34c049135ec0","order_by":0,"name":"Ingo 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Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Actin-dynamics, Actin-membrane interface, PIP5K2, Membrane-nanostructure, PIP2","lastPublishedDoi":"10.21203/rs.3.rs-7598484/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7598484/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The intersection of actin-filaments with the plasma membrane 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-plasma membrane contacts by modulating membrane lipid nano-organization. ATM2 binds both actin and phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2), a lipid required for ATM2-plasma membrane-attachment. 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 effects of full-length ATM2 on actin dynamics despite its retained plasma membrane-association. ATM2 colocalized and interacted with the PI4P 5-kinase, PIP5K2, which resides at actin-plasma membrane-contacts and forms PtdIns(4,5)P2-nanodomains facilitating ROP-dependent actin-stabilization. Upon ATM2-overexpression, a fluorescent PtdIns(4,5)P2-biosensor decorated an expanded plasma membrane-region in vivo, indicating a promoting effect of ATM2 on PtdIns(4,5)P2-abundance. Moreover, catalytic activity of purified recombinant PIP5K2 protein was enhanced upon coincubation with a purified C-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-plasma membrane interface by ATM2 locally promoting the formation of PtdIns(4,5)P2-nanodomains, thereby self-reinforcing ATM2-recruitment while also facilitating ROP-activation to stabilize membrane-proximal actin-filaments.","manuscriptTitle":"The class VIII myosin ATM2 stabilizes actin-plasma membrane contacts by locally promoting PtdIns(4,5)P2 nanodomain formation in tobacco pollen tubes","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-07 12:30:29","doi":"10.21203/rs.3.rs-7598484/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"nature-plants","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"nplants","sideBox":"Learn more about [Nature Plants](http://www.nature.com/nplants/)","snPcode":"","submissionUrl":"","title":"Nature Plants","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature Research","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"fc16bc93-d953-45f7-91a7-f17353d33928","owner":[],"postedDate":"October 7th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":55802824,"name":"Biological sciences/Cell biology/Cell signalling/Lipid signalling"},{"id":55802825,"name":"Biological sciences/Cell biology/Cell signalling/Phosphoinositol signalling"}],"tags":[],"updatedAt":"2026-01-22T13:11:10+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-07 12:30:29","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7598484","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7598484","identity":"rs-7598484","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}