Directionality in the intercellular transport of the plant hormone auxin is determined by polar plasma membrane localization of PIN-FORMED (PIN) auxin transport proteins. However, apart from PIN phosphorylation at conserved motifs, no further determinants explicitly controlling polar PIN sorting decisions have been identified. Here we present Arabidopsis WAVY GROWTH 3 (WAV3) and closely related RING-finger E3 ubiquitin ligases, whose loss-of-function mutants show a striking apical-to-basal polarity switch in PIN2 localization in root meristem cells. WAV3 E3 ligases function as essential determinants for PIN polarity, acting independently from PINOID/WAG-dependent PIN phosphorylation. They antagonize ectopic deposition of de novo synthesized PIN proteins already immediately following completion of cell division, presumably via preventing PIN sorting into basal, ARF GEF-mediated trafficking. Our findings reveal an involvement of E3 ligases in the selective targeting of apically localized PINs in higher plants.
- MeSH
- Arabidopsis * metabolismus MeSH
- kořeny rostlin metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- proteiny huseníčku * genetika metabolismus MeSH
- transport proteinů MeSH
- ubikvitinligasy genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kyseliny indoloctové MeSH
- proteiny huseníčku * MeSH
- ubikvitinligasy MeSH
Growing evidence has highlighted the essential role of plant hormones, notably, cytokinins (CKs), in nitrogen-fixing symbiosis, both at early and late nodulation stages1,2. Despite numerous studies showing the central role of CK in nodulation, the importance of CK transport in the symbiosis is unknown. Here, we show the role of ABCG56, a full-size ATP-binding cassette (ABC) transporter in the early stages of the nodulation. MtABCG56 is expressed in roots and nodules and its messenger RNA levels increase upon treatment with symbiotic bacteria, isolated Nod factor and CKs, accumulating within the epidermis and root cortex. MtABCG56 exports bioactive CKs in an ATP-dependent manner over the plasma membrane and its disruption results in an impairment of nodulation. Our data indicate that ABCG-mediated cytokinin transport is important for proper establishment of N-fixing nodules.
- MeSH
- ABC transportér, podrodina G genetika metabolismus MeSH
- biologický transport MeSH
- cytokininy metabolismus MeSH
- fixace dusíku MeSH
- Medicago truncatula genetika mikrobiologie MeSH
- regulátory růstu rostlin metabolismus MeSH
- Rhizobium fyziologie MeSH
- rostlinné proteiny genetika metabolismus MeSH
- symbióza genetika MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- ABC transportér, podrodina G MeSH
- cytokininy MeSH
- regulátory růstu rostlin MeSH
- rostlinné proteiny MeSH
The widely used non-steroidal anti-inflammatory drugs (NSAIDs) are derivatives of the phytohormone salicylic acid (SA). SA is well known to regulate plant immunity and development, whereas there have been few reports focusing on the effects of NSAIDs in plants. Our studies here reveal that NSAIDs exhibit largely overlapping physiological activities to SA in the model plant Arabidopsis. NSAID treatments lead to shorter and agravitropic primary roots and inhibited lateral root organogenesis. Notably, in addition to the SA-like action, which in roots involves binding to the protein phosphatase 2A (PP2A), NSAIDs also exhibit PP2A-independent effects. Cell biological and biochemical analyses reveal that many NSAIDs bind directly to and inhibit the chaperone activity of TWISTED DWARF1, thereby regulating actin cytoskeleton dynamics and subsequent endosomal trafficking. Our findings uncover an unexpected bioactivity of human pharmaceuticals in plants and provide insights into the molecular mechanism underlying the cellular action of this class of anti-inflammatory compounds.
- Klíčová slova
- Arabidopsis, FKBP, NSAID, TWD1, actin filament, auxin, auxin transport inhibitor, endosomal trafficking, non-steroidal anti-inflammatory drug, polar auxin transport,
- MeSH
- aktiny metabolismus MeSH
- antiflogistika nesteroidní farmakologie terapeutické užití MeSH
- Arabidopsis MeSH
- kyseliny indoloctové metabolismus MeSH
- proteiny huseníčku metabolismus MeSH
- proteiny vázající takrolimus metabolismus MeSH
- vývoj rostlin MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- aktiny MeSH
- antiflogistika nesteroidní MeSH
- kyseliny indoloctové MeSH
- proteiny huseníčku MeSH
- proteiny vázající takrolimus MeSH
- TWD1 protein, Arabidopsis MeSH Prohlížeč
Plant growth and architecture is regulated by the polar distribution of the hormone auxin. Polarity and flexibility of this process is provided by constant cycling of auxin transporter vesicles along actin filaments, coordinated by a positive auxin-actin feedback loop. Both polar auxin transport and vesicle cycling are inhibited by synthetic auxin transport inhibitors, such as 1-N-naphthylphthalamic acid (NPA), counteracting the effect of auxin; however, underlying targets and mechanisms are unclear. Using NMR, we map the NPA binding surface on the Arabidopsis thaliana ABCB chaperone TWISTED DWARF1 (TWD1). We identify ACTIN7 as a relevant, although likely indirect, TWD1 interactor, and show TWD1-dependent regulation of actin filament organization and dynamics and that TWD1 is required for NPA-mediated actin cytoskeleton remodeling. The TWD1-ACTIN7 axis controls plasma membrane presence of efflux transporters, and as a consequence act7 and twd1 share developmental and physiological phenotypes indicative of defects in auxin transport. These can be phenocopied by NPA treatment or by chemical actin (de)stabilization. We provide evidence that TWD1 determines downstream locations of auxin efflux transporters by adjusting actin filament debundling and dynamizing processes and mediating NPA action on the latter. This function appears to be evolutionary conserved since TWD1 expression in budding yeast alters actin polarization and cell polarity and provides NPA sensitivity.
- MeSH
- Arabidopsis genetika metabolismus MeSH
- biologický transport genetika fyziologie MeSH
- kyseliny indoloctové metabolismus MeSH
- mikrofilamenta metabolismus MeSH
- proteiny huseníčku genetika metabolismus MeSH
- proteiny vázající takrolimus genetika metabolismus MeSH
- regulace genové exprese u rostlin genetika fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kyseliny indoloctové MeSH
- proteiny huseníčku MeSH
- proteiny vázající takrolimus MeSH
- TWD1 protein, Arabidopsis MeSH Prohlížeč
