Complementation of the embryo-lethal T-DNA insertion mutant of AUXIN-BINDING-PROTEIN 1 (ABP1) with abp1 point mutated versions reveals crosstalk of ABP1 and phytochromes

Effendi, Yunus; Ferro, Noel; Labusch, Corinna; Geisler, Markus; Scherer, Günther F. E.

doi:10.1093/jxb/eru433

Cited by 10 publications

(20 citation statements)

References 59 publications

(114 reference statements)

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“…abp1-5 displays red light phenotypes consistent with ABP1 roles in light signaling (Effendi et al, 2013(Effendi et al, , 2015. In particular, abp1-5 displays longer hypocotyls under red light (Effendi et al, 2013; Figure 1).…”

Section: Abp1-5 Light Signaling Defects Are Likely Caused By a Secondmentioning

confidence: 63%

Genome Sequencing of Arabidopsis abp1-5 Reveals Second-Site Mutations That May Affect Phenotypes

Enders

Yang

et al. 2015

The Plant Cell

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Auxin regulates numerous aspects of plant growth and development. For many years, investigating roles for AUXIN BINDING PROTEIN1 (ABP1) in auxin response was impeded by the reported embryo lethality of mutants defective in ABP1. However, identification of a viable Arabidopsis thaliana TILLING mutant defective in the ABP1 auxin binding pocket (abp1-5) allowed inroads into understanding ABP1 function. During our own studies with abp1-5, we observed growth phenotypes segregating independently of the ABP1 lesion, leading us to sequence the genome of the abp1-5 line described previously. We found that the abp1-5 line we sequenced contains over 8000 single nucleotide polymorphisms in addition to the ABP1 mutation and that at least some of these mutations may originate from the Arabidopsis Wassilewskija accession. Furthermore, a phyB null allele in the abp1-5 background is likely causative for the long hypocotyl phenotype previously attributed to disrupted ABP1 function. Our findings complicate the interpretation of abp1-5 phenotypes for which no complementation test was conducted. Our findings on abp1-5 also provide a cautionary tale illustrating the need to use multiple alleles or complementation lines when attributing roles to a gene product. INTRODUCTIONThe plant hormone auxin regulates cell division and cell expansion to affect all aspects of plant growth (reviewed in PerrotRechenmann, 2010). Auxin regulates a wide range of developmental processes, and tight control of auxin response is maintained by multiple modes of regulation. These include regulating auxin biosynthesis and metabolism, transport, and signaling (reviewed in Enders and Strader, 2015). To date, nuclear auxin signaling components have been well characterized (reviewed in Chapman and Estelle, 2009;Salehin et al., 2015). In addition, a nontranscriptional auxin response pathway has been proposed, with AUXIN BINDING PROTEIN1 (ABP1) acting in the apoplast as an auxin receptor and transmitting a cytoplasmic signal to regulate auxin responses such as auxin transport and cytoskeletal rearrangements (reviewed in Shi and Yang, 2011;Sauer et al., 2013).Study of ABP1 has a long, complicated history. Experiments demonstrating auxin binding activity for ABP1 were published as early as the 1980s (reviewed in Jones, 1994). Reverse genetics proved to be a complicated approach to study ABP1 function in Arabidopsis thaliana, as two independently generated abp1 mutants, presumed to be null alleles, appeared to be embryo lethal (Chen et al., 2001;Tzafrir et al., 2004;Meinke et al., 2008;Sassi et al., 2014). Knockdown lines of ABP1 provided some ability to study ABP1 function by reverse genetics. Arabidopsis lines expressing an inducible ABP1 antisense transcript or an inducible single-chain fragment variable scFv12 (David et al., 2007) from a monoclonal antibody raised to ABP1 (Leblanc et al., 1999), targeted to either the apoplast (SS12S) or the endoplasmic reticulum (SS12K), led to phenotypes consistent with decreased auxin activity (Braun et al., 2008;Tromas et al.,...

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Section: Abp1-5 Light Signaling Defects Are Likely Caused By a Secondmentioning

confidence: 63%

Genome Sequencing of Arabidopsis abp1-5 Reveals Second-Site Mutations That May Affect Phenotypes

Enders

Yang

et al. 2015

The Plant Cell

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“…In previous studies, ABP1 knockdown was associated with a number of developmental defects including changes in root and hypocotyl elongation, leaf expansion, and maintenance of the root meristem (4,10,11,(20)(21)(22)(23). To determine whether abp1-c1 plants exhibited any of these defects, we compared them to WT plants grown under the same growth conditions.…”

Section: Resultsmentioning

confidence: 99%

Auxin binding protein 1 (ABP1) is not required for either auxin signaling or Arabidopsis development

Gao¹,

Zhang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

323

278

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Auxin binding protein 1 (ABP1) has been studied for decades. It has been suggested that ABP1 functions as an auxin receptor and has an essential role in many developmental processes. Here we present our unexpected findings that ABP1 is neither required for auxin signaling nor necessary for plant development under normal growth conditions. We used our ribozyme-based CRISPR technology to generate an Arabidopsis abp1 mutant that contains a 5-bp deletion in the first exon of ABP1, which resulted in a frameshift and introduction of early stop codons. We also identified a T-DNA insertion abp1 allele that harbors a T-DNA insertion located 27 bp downstream of the ATG start codon in the first exon. We show that the two new abp1 mutants are null alleles. Surprisingly, our new abp1 mutant plants do not display any obvious developmental defects. In fact, the mutant plants are indistinguishable from wild-type plants at every developmental stage analyzed. Furthermore, the abp1 plants are not resistant to exogenous auxin. At the molecular level, we find that the induction of known auxin-regulated genes is similar in both wild-type and abp1 plants in response to auxin treatments. We conclude that ABP1 is not a key component in auxin signaling or Arabidopsis development.

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“…Further, we used quantum chemical modeling based on density functional theory including dispersion correction terms (DFT-D; Effendi et al, 2015) to optimize the binding geometry of the NPA interaction using the crystal structure of the TWD1 FKBD (PDB 2F4E; Weiergräber et al, 2006) as the basis. The statistical analyses of different components of the quantum chemical forces and the electron density distribution in the region of interaction pocket-NPA deformation suggest that Van der Waals forces (ΔE VdW ) are primarily responsible for NPA binding to the TWD1 surface (Supplemental Figure 3), as has been recently proposed for other small molecule-protein interactions using thermodynamic data (Barratt et al, 2005).…”

Section: Resultsmentioning

confidence: 99%

TWISTED DWARF1 Mediates the Action of Auxin Transport Inhibitors on Actin Cytoskeleton Dynamics

et al. 2016

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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 auxinactin feedback loop. Both polar auxin transport and vesicle cycling are inhibited by synthetic auxin transport inhibitors, such as 1-Nnaphthylphthalamic 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.

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Complementation of the embryo-lethal T-DNA insertion mutant of AUXIN-BINDING-PROTEIN 1 (ABP1) with abp1 point mutated versions reveals crosstalk of ABP1 and phytochromes

Abstract: SummaryAUXIN BINDING PROTEIN1 (ABP1) mutants have properties of auxin- and red light-signalling mutants. A novel concept for growth control by ABP1 and phytochromes is indicated by this functional link.

Cited by 10 publications

References 59 publications

Genome Sequencing of Arabidopsis abp1-5 Reveals Second-Site Mutations That May Affect Phenotypes

Genome Sequencing of Arabidopsis abp1-5 Reveals Second-Site Mutations That May Affect Phenotypes

Auxin binding protein 1 (ABP1) is not required for either auxin signaling or Arabidopsis development

TWISTED DWARF1 Mediates the Action of Auxin Transport Inhibitors on Actin Cytoskeleton Dynamics

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