Nejvíce citovaný článek - PubMed ID 16601150
PIN proteins perform a rate-limiting function in cellular auxin efflux
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
Much of plant development depends on cell-to-cell redistribution of the plant hormone auxin, which is facilitated by the plasma membrane (PM) localized PIN FORMED (PIN) proteins. Auxin export activity, developmental roles, subcellular trafficking, and polarity of PINs have been well studied, but their structure remains elusive besides a rough outline that they contain two groups of 5 alpha-helices connected by a large hydrophilic loop (HL). Here, we focus on the PIN1 HL as we could produce it in sufficient quantities for biochemical investigations to provide insights into its secondary structure. Circular dichroism (CD) studies revealed its nature as an intrinsically disordered protein (IDP), manifested by the increase of structure content upon thermal melting. Consistent with IDPs serving as interaction platforms, PIN1 loops homodimerize. PIN1 HL cytoplasmic overexpression in Arabidopsis disrupts early endocytic trafficking of PIN1 and PIN2 and causes defects in the cotyledon vasculature formation. In summary, we demonstrate that PIN1 HL has an intrinsically disordered nature, which must be considered to gain further structural insights. Some secondary structures may form transiently during pairing with known and yet-to-be-discovered interactors.
- Klíčová slova
- PIN1, dimerization, hydrophilic hoop, intrinsic disorder, subcellular trafficking,
- MeSH
- Arabidopsis * metabolismus MeSH
- biologický transport MeSH
- kořeny rostlin metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- membránové transportní proteiny genetika metabolismus MeSH
- proteiny huseníčku * genetika metabolismus MeSH
- vnitřně neuspořádané proteiny * genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- kyseliny indoloctové MeSH
- membránové transportní proteiny MeSH
- PIN1 protein, Arabidopsis MeSH Prohlížeč
- proteiny huseníčku * MeSH
- vnitřně neuspořádané proteiny * MeSH
The root is the below-ground organ of a plant, and it has evolved multiple signaling pathways that allow adaptation of architecture, growth rate, and direction to an ever-changing environment. Roots grow along the gravitropic vector towards beneficial areas in the soil to provide the plant with proper nutrients to ensure its survival and productivity. In addition, roots have developed escape mechanisms to avoid adverse environments, which include direct illumination. Standard laboratory growth conditions for basic research of plant development and stress adaptation include growing seedlings in Petri dishes on medium with roots exposed to light. Several studies have shown that direct illumination of roots alters their morphology, cellular and biochemical responses, which results in reduced nutrient uptake and adaptability upon additive stress stimuli. In this review, we summarize recent methods that allow the study of shaded roots under controlled laboratory conditions and discuss the observed changes in the results depending on the root illumination status.
- Klíčová slova
- D-rootsystem, abiotic stress, auxin, cytokinin, dark-grown roots, direct root illumination, flavonols, light escape mechanism, reactive oxygen species, root growth,
- MeSH
- fyziologická adaptace * MeSH
- kořeny rostlin metabolismus účinky záření MeSH
- regulace genové exprese u rostlin účinky záření MeSH
- rostlinné proteiny genetika metabolismus MeSH
- rostliny metabolismus účinky záření MeSH
- semenáček metabolismus účinky záření MeSH
- světlo * MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- rostlinné proteiny MeSH
To overcome nitrogen deficiency, legume roots establish symbiotic interactions with nitrogen-fixing rhizobia that are fostered in specialized organs (nodules). Similar to other organs, nodule formation is determined by a local maximum of the phytohormone auxin at the primordium site. However, how auxin regulates nodule development remains poorly understood. Here, we found that in soybean, (Glycine max), dynamic auxin transport driven by PIN-FORMED (PIN) transporter GmPIN1 is involved in nodule primordium formation. GmPIN1 was specifically expressed in nodule primordium cells and GmPIN1 was polarly localized in these cells. Two nodulation regulators, (iso)flavonoids trigger expanded distribution of GmPIN1b to root cortical cells, and cytokinin rearranges GmPIN1b polarity. Gmpin1abc triple mutants generated with CRISPR-Cas9 showed the impaired establishment of auxin maxima in nodule meristems and aberrant divisions in the nodule primordium cells. Moreover, overexpression of GmPIN1 suppressed nodule primordium initiation. GmPIN9d, an ortholog of Arabidopsis thaliana PIN2, acts together with GmPIN1 later in nodule development to acropetally transport auxin in vascular bundles, fine-tuning the auxin supply for nodule enlargement. Our findings reveal how PIN-dependent auxin transport modulates different aspects of soybean nodule development and suggest that the establishment of auxin gradient is a prerequisite for the proper interaction between legumes and rhizobia.
- MeSH
- biologický transport MeSH
- Glycine max genetika růst a vývoj metabolismus MeSH
- kořenové hlízky rostlin růst a vývoj metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- rostlinné proteiny genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kyseliny indoloctové MeSH
- rostlinné proteiny MeSH
Together with auxin transport, auxin metabolism is a key determinant of auxin signaling output by plant cells. Enzymatic machinery involved in auxin metabolism is subject to regulation based on numerous inputs, including the concentration of auxin itself. Therefore, experiments characterizing altered auxin availability and subsequent changes in auxin metabolism could elucidate the function and regulatory role of individual elements in the auxin metabolic machinery. Here, we studied auxin metabolism in auxin-dependent tobacco BY-2 cells. We revealed that the concentration of N-(2-oxindole-3-acetyl)-l-aspartic acid (oxIAA-Asp), the most abundant auxin metabolite produced in the control culture, dramatically decreased in auxin-starved BY-2 cells. Analysis of the transcriptome and proteome in auxin-starved cells uncovered significant downregulation of all tobacco (Nicotiana tabacum) homologs of Arabidopsis (Arabidopsis thaliana) DIOXYGENASE FOR AUXIN OXIDATION 1 (DAO1), at both transcript and protein levels. Auxin metabolism profiling in BY-2 mutants carrying either siRNA-silenced or CRISPR-Cas9-mutated NtDAO1, as well as in dao1-1 Arabidopsis plants, showed not only the expected lower levels of oxIAA, but also significantly lower abundance of oxIAA-Asp. Finally, ability of DAO1 to oxidize IAA-Asp was confirmed by an enzyme assay in AtDAO1-producing bacterial culture. Our results thus represent direct evidence of DAO1 activity on IAA amino acid conjugates.
De novo shoot organogenesis (DNSO) is a procedure commonly used for the in vitro regeneration of shoots from a variety of plant tissues. Shoot regeneration occurs on nutrient media supplemented with the plant hormones cytokinin (CK) and auxin, which play essential roles in this process, and genes involved in their signaling cascades act as master regulators of the different phases of shoot regeneration. In the last 20 years, the genetic regulation of DNSO has been characterized in detail. However, as of today, the CK and auxin signaling events associated with shoot regeneration are often interpreted as a consequence of these hormones simply being present in the regeneration media, whereas the roles for their prior uptake and transport into the cultivated plant tissues are generally overlooked. Additionally, sucrose, commonly added to the regeneration media as a carbon source, plays a signaling role and has been recently shown to interact with CK and auxin and to affect the efficiency of shoot regeneration. In this review, we provide an integrative interpretation of the roles for CK and auxin in the process of DNSO, adding emphasis on their uptake from the regeneration media and their interaction with sucrose present in the media to their complex signaling outputs that mediate shoot regeneration.
- Klíčová slova
- DNSO, auxin, cytokinin, de novo shoot organogenesis, gene regulatory network, hormone uptake, shoot regeneration, sucrose, transport,
- MeSH
- cytokininy metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- organogeneze rostlin * MeSH
- regulátory růstu rostlin metabolismus MeSH
- výhonky rostlin cytologie metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- cytokininy MeSH
- kyseliny indoloctové MeSH
- regulátory růstu rostlin MeSH
Auxin regulates the transcription of auxin-responsive genes by the TIR1/AFBs-Aux/IAA-ARF signaling pathway, and in this way facilitates plant growth and development. However, rapid, nontranscriptional responses to auxin that cannot be explained by this pathway have been reported. In this review, we focus on several examples of rapid auxin responses: (1) the triggering of changes in plasma membrane potential in various plant species and tissues, (2) inhibition of root growth, which also correlates with membrane potential changes, cytosolic Ca2+ spikes, and a rise of apoplastic pH, (3) the influence on endomembrane trafficking of PIN proteins and other membrane cargoes, and (4) activation of ROPs (Rho of plants) and their downstream effectors such as the cytoskeleton or vesicle trafficking. In most cases, the signaling pathway triggering the response is poorly understood. A role for the TIR1/AFBs in rapid root growth regulation is emerging, as well as the involvement of transmembrane kinases (TMKs) in the activation of ROPs. We discuss similarities and differences among these rapid responses and focus on their physiological significance, which remains an enigma in most cases.
- MeSH
- endocytóza MeSH
- kořeny rostlin růst a vývoj MeSH
- kyseliny indoloctové metabolismus MeSH
- membránové potenciály MeSH
- proteiny vázající GTP metabolismus MeSH
- receptory buněčného povrchu metabolismus MeSH
- rostlinné proteiny metabolismus MeSH
- rostliny metabolismus MeSH
- vápník metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Názvy látek
- auxin receptor, plant MeSH Prohlížeč
- kyseliny indoloctové MeSH
- proteiny vázající GTP MeSH
- receptory buněčného povrchu MeSH
- rostlinné proteiny MeSH
- vápník MeSH
Polar subcellular localization of the PIN exporters of the phytohormone auxin is a key determinant of directional, intercellular auxin transport and thus a central topic of both plant cell and developmental biology. Arabidopsis mutants lacking PID, a kinase that phosphorylates PINs, or the MAB4/MEL proteins of unknown molecular function display PIN polarity defects and phenocopy pin mutants, but mechanistic insights into how these factors convey PIN polarity are missing. Here, by combining protein biochemistry with quantitative live-cell imaging, we demonstrate that PINs, MAB4/MELs, and AGC kinases interact in the same complex at the plasma membrane. MAB4/MELs are recruited to the plasma membrane by the PINs and in concert with the AGC kinases maintain PIN polarity through limiting lateral diffusion-based escape of PINs from the polar domain. The PIN-MAB4/MEL-PID protein complex has self-reinforcing properties thanks to positive feedback between AGC kinase-mediated PIN phosphorylation and MAB4/MEL recruitment. We thus uncover the molecular mechanism by which AGC kinases and MAB4/MEL proteins regulate PIN localization and plant development.
- Klíčová slova
- Arabidopsis, cell polarity, lateral diffusion, plant development, polar auxin transport, positive feedback, protein phosphorylation,
- MeSH
- Arabidopsis * genetika metabolismus MeSH
- biologický transport MeSH
- kořeny rostlin metabolismus MeSH
- kyseliny indoloctové MeSH
- membránové transportní proteiny genetika MeSH
- polarita buněk MeSH
- proteiny huseníčku * genetika metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné buňky metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- kyseliny indoloctové MeSH
- membránové transportní proteiny MeSH
- proteiny huseníčku * MeSH
Plant growth and productivity are orchestrated by a network of signaling cascades involved in balancing responses to perceived environmental changes with resource availability. Vascular plants are divided into the shoot, an aboveground organ where sugar is synthesized, and the underground located root. Continuous growth requires the generation of energy in the form of carbohydrates in the leaves upon photosynthesis and uptake of nutrients and water through root hairs. Root hair outgrowth depends on the overall condition of the plant and its energy level must be high enough to maintain root growth. TARGET OF RAPAMYCIN (TOR)-mediated signaling cascades serve as a hub to evaluate which resources are needed to respond to external stimuli and which are available to maintain proper plant adaptation. Root hair growth further requires appropriate distribution of the phytohormone auxin, which primes root hair cell fate and triggers root hair elongation. Auxin is transported in an active, directed manner by a plasma membrane located carrier. The auxin efflux carrier PIN-FORMED 2 is necessary to transport auxin to root hair cells, followed by subcellular rearrangements involved in root hair outgrowth. This review presents an overview of events upstream and downstream of PIN2 action, which are involved in root hair growth control.
- Klíčová slova
- PIN-FORMED 2, ROP2, ROS, TOR signaling, auxin, plant adaptation, polar cell elongation, root growth, root hair growth,
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Directional intercellular transport of the phytohormone auxin mediated by PIN-FORMED (PIN) efflux carriers has essential roles in both coordinating patterning processes and integrating multiple external cues by rapidly redirecting auxin fluxes. PIN activity is therefore regulated by multiple internal and external cues, for which the underlying molecular mechanisms are not fully elucidated. Here, we demonstrate that 3'-PHOSPHOINOSITIDE-DEPENDENT PROTEIN KINASE1 (PDK1), which is conserved in plants and mammals, functions as a molecular hub that perceives upstream lipid signalling and modulates downstream substrate activity through phosphorylation. Using genetic analysis, we show that the loss-of-function Arabidopsis pdk1.1 pdk1.2 mutant exhibits a plethora of abnormalities in organogenesis and growth due to defective polar auxin transport. Further cellular and biochemical analyses reveal that PDK1 phosphorylates D6 protein kinase, a well-known upstream activator of PIN proteins. We uncover a lipid-dependent phosphorylation cascade that connects membrane-composition-based cellular signalling with plant growth and patterning by regulating morphogenetic auxin fluxes.
- MeSH
- Arabidopsis metabolismus MeSH
- buněčná membrána metabolismus MeSH
- fosfolipidy metabolismus MeSH
- kyseliny indoloctové metabolismus MeSH
- membránové transportní proteiny metabolismus fyziologie MeSH
- proteinkinasy PDK fyziologie MeSH
- proteiny huseníčku fyziologie MeSH
- regulátory růstu rostlin metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- fosfolipidy MeSH
- kyseliny indoloctové MeSH
- membránové transportní proteiny MeSH
- proteinkinasy PDK MeSH
- proteiny huseníčku MeSH
- regulátory růstu rostlin MeSH
