Rice DWARF14 acts as an unconventional hormone receptor for strigolactone.
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ABSTRACT:
SUBMITTER: Yao R
PROVIDER: S-EPMC5913607 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Strigolactones, a group of terpenoid lactones, control many aspects of plant growth and development, but the active forms of these plant hormones and their mode of action at the molecular level are still unknown. The strigolactone protein receptor is unusual because it has been shown to cleave the hormone and supposedly forms a covalent bond with the cleaved hormone fragment. This interaction is suggested to induce a conformational change in the receptor that primes it for subsequent interaction with partners in the signalling pathway. Substantial efforts have been invested into describing the interaction of synthetic strigolactone analogues with the receptor, resulting in a number of crystal structures. This investigation combines a re-evaluation of models in the Protein Data Bank with a search for new conditions that may permit the capture of a receptor-ligand complex. While weak difference density is frequently observed in the binding cavity, possibly due to a low-occupancy compound, the models often contain features not supported by the X-ray data. Thus, at this stage, we do not believe that any detailed deductions about the nature, conformation, or binding mode of the ligand can be made with any confidence.
| S-EPMC5913616 | biostudies-literature
Project description:The perception mechanism for the strigolactone (SL) class of plant hormones has been a subject of debate because their receptor, DWARF14 (D14), is an ?/?-hydrolase that can cleave SLs. Here we show via time-course analyses of SL binding and hydrolysis by Arabidopsis thaliana D14, that the level of uncleaved SL strongly correlates with the induction of the active signaling state. In addition, we show that an AtD14D218A catalytic mutant that lacks enzymatic activity is still able to complement the atd14 mutant phenotype in an SL-dependent manner. We conclude that the intact SL molecules trigger the D14 active signaling state, and we also describe that D14 deactivates bioactive SLs by the hydrolytic degradation after signal transmission. Together, these results reveal that D14 is a dual-functional receptor, responsible for both the perception and deactivation of bioactive SLs.
| S-EPMC6331613 | biostudies-literature
Project description:DWARF14 (D14) is a strigolactone receptor that plays a central role in suppression of shoot branching, and hence is a potential target to increase crop productions and biomass. Recently, we reported a fluorescence turn-on probe, Yoshimulactone Green (YLG), which generates a strong fluorescence upon the hydrolysis by D14-type strigolactone receptors. Herein, we applied a YLG-based in vitro assay to a high-throughput chemical screening and identified a novel small molecule DL1 as a potent inhibitor of D14. DL1 competes with endogenous strigolactones, thereby increasing the number of shoot branching in a model plant Arabidopsis as well as in rice. Thus, DL1 is expected to be useful not only as a tool to understand the biological roles of D14 receptors in plant growth and development, but also as a potent agrochemical to improve the crop yield.
| S-EPMC5833010 | biostudies-literature
Project description:Strigolactones (SLs) are the latest confirmed phytohormones that regulate shoot branching by inhibiting bud outgrowth in higher plants. Perception of SLs depends on a novel mechanism employing an enzyme-receptor DWARF14 (D14) that hydrolyzes SLs and becomes covalently modified. This stimulates the interaction between D14 and D3, leading to the ubiquitination and degradation of the transcriptional repressor protein D53. However, the regulation of SL perception in rice remains elusive. In this study, we provide evidences that D14 is ubiquitinated after SL treatment and degraded through the 26S proteasome system. The Lys280 site of the D14 amino acid sequence was important for SL-induced D14 degradation, but did not change the subcellular localization of D14 nor disturbed the interaction between D14 and D3, nor D53 degradation. Biochemical and genetic analysis indicated that the key amino acids in the catalytic center of D14 were essential for D14 degradation. We further showed that D14 degradation is dependent on D3 and is tightly correlated with protein levels of D53. These findings revealed that D14 degradation takes place following D53 degradation and functions as an important feedback regulation mechanism of SL perception in rice.
| S-EPMC5684176 | biostudies-literature
Project description:DWARF14 (D14) is an ɑ/β-hydrolase and receptor for the plant hormone strigolactone (SL) in angiosperms. Upon SL perception, D14 works with MORE AXILLARY GROWTH2 (MAX2) to trigger polyubiquitination and degradation of DWARF53(D53)-type proteins in the SUPPRESSOR OF MAX2 1-LIKE (SMXL) family. We used CRISPR-Cas9 to generate knockout alleles of the two homoeologous D14 genes in the Nicotiana benthamiana genome. The Nbd14a,b double mutant had several phenotypes that are consistent with the loss of SL perception in other plants, including increased axillary bud outgrowth, reduced height, shortened petioles, and smaller leaves. A ratiometric fluorescent reporter system was used to monitor degradation of SMXL7 from Arabidopsis thaliana (AtSMXL7) after transient expression in N. benthamiana and treatment with the strigolactone analog GR24. AtSMXL7 was degraded after treatment with GR245DS, which has the stereochemical configuration of natural SLs, as well as its enantiomer GR24 ent-5DS. In Nbd14a,b leaves, AtSMXL7 abundance was unaffected by rac-GR24 or either GR24 stereoisomer. Transient coexpression of AtD14 with the AtSMXL7 reporter in Nbd14a,b restored the degradation response to rac-GR24, but required an active catalytic triad. We used this platform to evaluate the ability of several AtD14 mutants that had not been characterized in plants to target AtSMXL7 for degradation.
| S-EPMC8948499 | biostudies-literature
Project description:Strigolactones (SLs) are endogenous hormones and exuded signaling molecules in plant responses to low levels of mineral nutrients. Key mediators of the SL signaling pathway in rice include the α/β-fold hydrolase DWARF 14 (D14) and the F-box component DWARF 3 (D3) of the ubiquitin ligase SCF(D3) that mediate ligand-dependent degradation of downstream signaling repressors. One perplexing feature is that D14 not only functions as the SL receptor but is also an active enzyme that slowly hydrolyzes diverse natural and synthetic SLs including GR24, preventing the crystallization of a binary complex of D14 with an intact SL as well as the ternary D14/SL/D3 complex. Here we overcome these barriers to derive a structural model of D14 bound to intact GR24 and identify the interface that is required for GR24-mediated D14-D3 interaction. The mode of GR24-mediated signaling, including ligand recognition, hydrolysis by D14, and ligand-mediated D14-D3 interaction, is conserved in structurally diverse SLs. More importantly, D14 is destabilized upon the binding of ligands and D3, thus revealing an unusual mechanism of SL recognition and signaling, in which the hormone, the receptor, and the downstream effectors are systematically destabilized during the signal transduction process.
| S-EPMC4650425 | biostudies-literature
Project description:Strigolactones (SLs) are a group of newly identified plant hormones that control plant shoot branching. SL signalling requires the hormone-dependent interaction of DWARF 14 (D14), a probable candidate SL receptor, with DWARF 3 (D3), an F-box component of the Skp-Cullin-F-box (SCF) E3 ubiquitin ligase complex. Here we report the characterization of a dominant SL-insensitive rice (Oryza sativa) mutant dwarf 53 (d53) and the cloning of D53, which encodes a substrate of the SCF(D3) ubiquitination complex and functions as a repressor of SL signalling. Treatments with GR24, a synthetic SL analogue, cause D53 degradation via the proteasome in a manner that requires D14 and the SCF(D3) ubiquitin ligase, whereas the dominant form of D53 is resistant to SL-mediated degradation. Moreover, D53 can interact with transcriptional co-repressors known as TOPLESS-RELATED PROTEINS. Our results suggest a model of SL signalling that involves SL-dependent degradation of the D53 repressor mediated by the D14-D3 complex.
| S-EPMC5802366 | biostudies-literature
Project description:BackgroundStrigolactones (SLs) are recently identified plant hormones modulating root and shoot branching. Besides their endogenous role within the producing organism, SLs are also key molecules in the communication of plants with arbuscular mycorrhizal (AM) fungi and parasitic weeds. In fact SLs are exuded into the rhizosphere where they act as a host-derived signal, stimulating the germination of the seeds of parasitic plants which would not survive in the absence of a host root to colonize. Similarly, their perception by AM fungi causes extensive hyphal branching; this is a prerequisite for effective root colonization, since it increases the number of potential contact points with the host surface. In spite of the crucial and multifaceted biological role of SLs, there is no information on the receptor(s) which bind(s) such active molecules, neither in the producing plants, or in parasitic weeds or AM fungi.ResultsIn this work, we applied homology modelling techniques to investigate the structure of the protein encoded by the gene Dwarf14, which was first identified in rice as conferring SLs insensitivity when mutated. The best sequence identity was with bacterial RsbQ. Both proteins belong to the superfamily of alpha/beta-fold hydrolases, some members of which play a role in the metabolism or signalling of plant hormones. The Dwarf14 (D14) structure was refined by means of molecular dynamics simulations. In order to support the hypothesis that D14 could be an endogenous SLs receptor, we performed docking experiments with a natural ligand.ConclusionsIt is suggested that D14 interacts with and thereby may act as a receptor for SLs in plants. This hypothesis offers a starting point to experimentally study the mechanism of its activity in vivo by means of structural, molecular and genetic approaches. Lastly, knowledge of the putative receptor structure will boost the research on analogues of the natural substrates as required for agricultural applications.
| S-EPMC3436726 | biostudies-literature
Project description:Strigolactones (SLs) and related butenolides, originally identified as active seed germination stimulants of parasitic weeds, play important roles in many aspects of plant development. Two members of the D14 α/β hydrolase protein family, DWARF14 (D14) and KARRIKIN INSENSITIVE2 (KAI2) are essential for SL/butenolide signaling. The third member of the family in Arabidopsis, DWARF 14-LIKE2 (DLK2) is structurally very similar to D14 and KAI2, but its function is unknown. We demonstrated that DLK2 does not bind nor hydrolyze natural (+)5-deoxystrigol [(+)5DS], and weakly hydrolyzes non-natural strigolactone (-)5DS. A detailed genetic analysis revealed that DLK2 does not affect SL responses and can regulate seedling photomorphogenesis. DLK2 is upregulated in the dark dependent upon KAI2 and PHYTOCHROME INTERACTING FACTORS (PIFs), indicating that DLK2 might function in light signaling pathways. In addition, unlike its paralog proteins, DLK2 is not subject to rac-GR24-induced degradation, suggesting that DLK2 acts independently of MORE AXILLARY GROWTH2 (MAX2); however, regulation of DLK2 transcription is mostly accomplished through MAX2. In conclusion, these data suggest that DLK2 represents a divergent member of the DWARF14 family.
| S-EPMC5609103 | biostudies-literature
Project description:Rice tillering is a multigenic trait that influences grain yield, but its regulation molecular module is poorly understood. Here we report that OsMADS57 interacts with OsTB1 (TEOSINTE BRANCHED1) and targets D14 (Dwarf14) to control the outgrowth of axillary buds in rice. An activation-tagged mutant osmads57-1 and OsMADS57-overexpression lines showed increased tillers, whereas OsMADS57 antisense lines had fewer tillers. OsMIR444a-overexpressing lines exhibited suppressed OsMADS57 expression and tillering. Furthermore, osmads57-1 was insensitive to strigolactone treatment to inhibit axillary bud outgrowth, and OsMADS57's function in tillering was dependent on D14. D14 expression was downregulated in osmads57-1, but upregulated in antisense and OsMIR444a-overexpressing lines. OsMADS57 bound to the CArG motif [C(A/T)TTAAAAAG] in the promoter and directly suppressed D14 expression. Interaction of OsMADS57 with OsTB1 reduced OsMADS57 inhibition of D14 transcription. Therefore, OsMIR444a-regulated OsMADS57, together with OsTB1, target D14 to control tillering. This regulation mechanism could have important application in rice molecular breeding programs focused on high grain yield.
| S-EPMC3615354 | biostudies-literature