A <i>Selaginella moellendorffii</i> Ortholog of KARRIKIN INSENSITIVE2 Functions in Arabidopsis Development but Cannot Mediate Responses to Karrikins or Strigolactones

Waters, Mark T.; Scaffidi, Adrian; Moulin, Solène; Sun, Yueming K.; Flematti, Gavin R.; Smith, Steven M.

doi:10.1105/tpc.15.00146

Cited by 124 publications

(224 citation statements)

References 53 publications

(102 reference statements)

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“…Mutation of the catalytic triad residues renders D14 nonfunctional as an enzyme, and also as a transducer of strigolactone signalling in planta (Hamiaux et al 2012). A critical observation is that binding of strigolactone to D14 induces a marked change in protein melting temperature, suggesting that the ligand-protein interaction imparts a change in D14 conformation (Hamiaux et al 2012;Zhao et al 2013;Abe et al 2014;Waters et al 2015b). Consistent with this interpretation, crystallography demonstrated the ligand-dependent interaction of D14 and D3/MAX2, together with the Arabidopsis SCF.…”

Section: Kai2 and D14 Are Both Receptor Proteins And Enzymessupporting

confidence: 62%

“…GR24 ent-5DS can substitute for karrikins in a range of KAI2-dependent assays, albeit with reduced sensitivity Waters et al 2015aWaters et al , 2015b. Likewise, D14 responds preferentially to GR24 5DS over GR24 ent-5DS (Nakamura et al 2013;Scaffidi et al 2014;Waters et al 2015b;Zhao et al 2015). The biological significance of KAI2 recognising non-naturallyconfigured strigolactones is unclear, but it does demonstrate that KAI2 and D14 exhibit distinct substrate preferences, which in part explains their functional differences.…”

Section: : Kai2/htl and D14mentioning

confidence: 96%

“…KAI2 is an active hydrolase, and mutagenesis of the catalytic triad renders it inactive both in vitro as an enzyme and in planta as a signal transducer (Waters et al 2015a(Waters et al , 2015b. Several studies have detected direct interaction between KAR 1 and KAI2 homologues using isothermal calorimetry and/or fluorescence-based binding assays (Guo et al 2013;Kagiyama et al 2013;Xu et al 2016).…”

Section: Kai2 and D14 Are Both Receptor Proteins And Enzymesmentioning

confidence: 99%

“…These mirror images, or enantiomers, have been given the simplified names of GR24 5DS and GR24 ent-5DS , respectively, in reference to the natural strigolactone 5-deoxystrigol (5DS) that they most closely resemble Flematti et al 2016). GR24 ent-5DS can substitute for karrikins in a range of KAI2-dependent assays, albeit with reduced sensitivity Waters et al 2015aWaters et al , 2015b. Likewise, D14 responds preferentially to GR24 5DS over GR24 ent-5DS (Nakamura et al 2013;Scaffidi et al 2014;Waters et al 2015b;Zhao et al 2015).…”

Section: : Kai2/htl and D14mentioning

confidence: 99%

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From little things big things grow: karrikins and new directions in plant development

Waters¹

2017

Functional Plant Biol.

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Abstract. Karrikins are a family of compounds generated via the incomplete combustion of plant matter. Since their discovery as seed germination stimulants in 2004, a great deal has been learned about the chemistry and the biological mode of action of karrikins. Much interest and progress have stemmed from the structural similarity of karrikins to that of strigolactones -the shoot branching hormone. This review will provide a historical account of some of the more significant discoveries in this area of plant biology. It will discuss how the study of these abiotic signalling molecules, combined with advances in our understanding of strigolactones, has led us towards the discovery of new mechanisms that regulate plant growth and development.

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Section: Kai2 and D14 Are Both Receptor Proteins And Enzymessupporting

confidence: 62%

Section: : Kai2/htl and D14mentioning

confidence: 96%

Section: Kai2 and D14 Are Both Receptor Proteins And Enzymesmentioning

confidence: 99%

Section: : Kai2/htl and D14mentioning

confidence: 99%

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From little things big things grow: karrikins and new directions in plant development

Waters¹

2017

Functional Plant Biol.

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“…While the catalytic serine of KAI2 is required for karrikin signaling [35], in the KAI2/karrikin complex structure, karrikin stably binds to the pocket at a position distal from the catalytic triad [23]. In further contrast to D14/GR24, karrikin binding appears to induce significant conformational changes in ten residues of the lid domain [23] that are poorly conserved in D14 (Supplementary information, Figure S9).…”

Section: Discussionmentioning

confidence: 83%

Destabilization of strigolactone receptor DWARF14 by binding of ligand and E3-ligase signaling effector DWARF3

et al. 2015

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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.

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Karrikins: Germination Stimulants Produced by Wildfires

Smith¹

2019

Encyclopedia of Life Sciences

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Karrikins are simple organic chemicals produced by wildfires that stimulate germination of dormant seeds in the soil. They are present in the smoke and char produced by the fire and are washed into the soil by the following rains. Many plant species have evolved such that their seeds remain dormant in the soil until they encounter karrikins, whereupon they can germinate. This strategy has the advantage that emerging seedlings will have plenty of light and a supply of nutrients released by the fire. Such plants are termed ‘fire ephemerals’ because they appear after fires, then flower, produce seed and die. It is believed that karrikins mimic an unidentified endogenous germination hormone. Karrikins are also similar to endogenous hormones called strigolactones that control plant development. Karrikin perception by seeds apparently requires a protein closely related to the strigolactone receptor. Karrikins or smoke can be used to stimulate germination in horticulture and landscape revegetation. Key Concepts Wildfires stimulate seeds in the soil to germinate which contributes to rapid revegetation. Seeds from many plant species are adapted to respond to chemicals produced by fire. The most active germination stimulant produced by wildfires is a butenolide named ‘karrikin’. Karrikins can influence germination and also seedling development. The receptor protein and molecular components of the response pathway have been identified. Karrikins mimic an ancient endogenous plant hormone that has not yet been identified. Karrikins stimulate germination of agricultural weeds and so might be useful for their control. Karrikins provide tools and knowledge to help us manage our natural landscapes. Karrikins might be useful in seed conservation work and in seed banks. The karrikin signalling system might be applied in crop breeding for environmental resilience.

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A Selaginella moellendorffii Ortholog of KARRIKIN INSENSITIVE2 Functions in Arabidopsis Development but Cannot Mediate Responses to Karrikins or Strigolactones

Cited by 124 publications

References 53 publications

From little things big things grow: karrikins and new directions in plant development

From little things big things grow: karrikins and new directions in plant development

Destabilization of strigolactone receptor DWARF14 by binding of ligand and E3-ligase signaling effector DWARF3

Karrikins: Germination Stimulants Produced by Wildfires

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