Functional analysis of Arabidopsis genes involved in mitochondrial iron–sulfur cluster assembly

Frazzon, Ana Paula Guedes; Ramirez, Melissa V.; Warek, Ujwala; Balk, Janneke; Frazzon, Jeverson; Dean, Dennis R.; Winkel, Brenda S.J.

doi:10.1007/s11103-007-9147-x

Cited by 52 publications

(52 citation statements)

References 67 publications

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“…Also, we found that mitochondrial ACO activity was decreased. The mitochondria contain their own Fe-S cluster assembly machinery, which functions upstream of the CIA machinery in yeast and plants (Frazzon et al, 2007;Lill, 2009). However, regulatory feedback mechanisms may exist: For example, if the cytosolic Fe-S cluster assembly pathway is impaired, the production of precursors by the mitochondrial iron-sulfur cluster machinery may be downregulated to prevent accumulation of the substrate of ATM3 or other intermediates.…”

Section: Discussionmentioning

confidence: 99%

The DUF59 Family Gene AE7 Acts in the Cytosolic Iron-Sulfur Cluster Assembly Pathway to Maintain Nuclear Genome Integrity in Arabidopsis

et al. 2012

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Eukaryotic organisms have evolved a set of strategies to safeguard genome integrity, but the underlying mechanisms remain poorly understood. Here, we report that ASYMMETRIC LEAVES1/2 ENHANCER7 (AE7), an Arabidopsis thaliana gene encoding a protein in the evolutionarily conserved Domain of Unknown Function 59 family, participates in the cytosolic ironsulfur (Fe-S) cluster assembly (CIA) pathway to maintain genome integrity. The severe ae7-2 allele is embryo lethal, whereas plants with the weak ae7 (ae7-1) allele are viable but exhibit highly accumulated DNA damage that activates the DNA damage response to arrest the cell cycle. AE7 is part of a protein complex with CIA1, NAR1, and MET18, which are highly conserved in eukaryotes and are involved in the biogenesis of cytosolic and nuclear Fe-S proteins. ae7-1 plants have lower activities of the cytosolic [4Fe-4S] enzyme aconitase and the nuclear [4Fe-4S] enzyme DNA glycosylase ROS1. Additionally, mutations in the gene encoding the mitochondrial ATP binding cassette transporter ATM3/ABCB25, which is required for the activity of cytosolic Fe-S enzymes in Arabidopsis, also result in defective genome integrity similar to that of ae7-1. These results indicate that AE7 is a central member of the CIA pathway, linking plant mitochondria to nuclear genome integrity through assembly of Fe-S proteins.

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Section: Discussionmentioning

confidence: 99%

The DUF59 Family Gene AE7 Acts in the Cytosolic Iron-Sulfur Cluster Assembly Pathway to Maintain Nuclear Genome Integrity in Arabidopsis

et al. 2012

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“…It has been proposed that in mammals alternative splicing mechanisms provide small amounts of ISC protein isoforms in the cytosol. However, localization data of various ISC proteins in Arabidopsis argue against this possibility in plants (23,34,35). Moreover, recent reports in mammals show that cytosolic Fe-S protein assembly is dependent on the mitochondrial ISC machinery rather than the cytosolic ISC isoforms (36,37).…”

Section: Discussionmentioning

confidence: 99%

The Essential Cytosolic Iron-Sulfur Protein Nbp35 Acts without Cfd1 Partner in the Green Lineage

Bych

Netz

Vigani

et al. 2008

Journal of Biological Chemistry

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In photosynthetic eukaryotes assembly components of ironsulfur (Fe-S) cofactors have been studied in plastids and mitochondria, but how cytosolic and nuclear Fe-S cluster proteins are assembled is not known. We have characterized a plant P loop NTPase with sequence similarity to Nbp35 of yeast and mammals, a protein of the cytosolic Cfd1-Nbp35 complex mediating Fe-S cluster assembly. Genome analysis revealed that NBP35 is conserved in the green lineage but that CFD1 is absent. Moreover, plant and algal NBP35 proteins lack the characteristic CXXC motif in the C terminus, thought to be required for Fe-S cluster binding. Nevertheless, chemical reconstitution and spectroscopy showed that Arabidopsis (At) NBP35 bound a [4Fe-4S] cluster in the C terminus as well as a stable [4Fe-4S] cluster in the N terminus. Holo-AtNBP35 was able to transfer an Fe-S cluster to an apoprotein in vitro. When expressed in yeast, AtNBP35 bound 55 Fe dependent on the cysteine desulfurase Nfs1 and was able to partially rescue the growth of a cfd1 mutant but not of an nbp35 mutant. The AtNBP35 gene is constitutively expressed in planta, and its disruption was associated with an arrest of embryo development. These results show that despite considerable divergence from the yeast Cfd1-Nbp35 Fe-S scaffold complex, AtNBP35 has retained similar Fe-S cluster binding and transfer properties and performs an essential function.Proteins carrying iron-sulfur (Fe-S) clusters as cofactors are common in virtually all life forms. Fe-S proteins catalyze crucial steps in fundamental processes, including nitrogen fixation, respiration, photosynthesis, various metabolic pathways, and regulation of gene expression (1). The most common types of Fe-S clusters are the [2Fe-2S] and the cubane [4Fe-4S] form. Although Fe-S clusters can be assembled by chemical means, dedicated proteins for in vivo Fe-S protein maturation have been discovered over the past 10 years (2, 3). In plants assembly proteins have been localized to the plastids and mitochondria, the endosymbiotic organelles where photosynthesis and respiration take place, respectively (for review, see Refs. 4 -6). The plastids contain all six proteins of the so-called SUF system plus NFU-type scaffolds. The mitochondrial matrix contains the ISC 3 system (for iron-sulfur cluster assembly). Both systems appear to follow the same biochemical steps; (i) generation of persulfide by a cysteine desulfurase (the Nfs1-Isd11 complex in mitochondria; CpNifS in plastids), (ii) transfer of persulfide and combination with iron to form an Fe-S cluster on a scaffold protein (ISU proteins in mitochondria; NFU2 in plastids), (iii) transfer of the Fe-S cluster from the scaffold protein to a target protein (mediated by chaperones in the ISC system).Important Fe-S enzymes are also found in the cytosol and nucleus (3, 4). In plants, these include DNA repair enzymes, RNA polymerase I and III (7), xanthine dehydrogenase, abscisic aldehyde oxidase (AAO3), and cytosolic aconitase. How these proteins obtain their Fe-S clusters is current...

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“…Selection of transformants for resistance to Basta was carried out on T1 seedlings as described previously (Frazzon et al, 2007). Genomic DNA was extracted from putative transformants (Edwards et al, 1991) and analyzed by PCR using primers specific for the transgene.…”

Section: Construction Of Transgenic Arabidopsis Plants Expressing Chsmentioning

confidence: 99%

Auxin and Ethylene Induce Flavonol Accumulation through Distinct Transcriptional Networks

et al. 2011

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Auxin and ethylene are key regulators of plant growth and development, and thus the transcriptional networks that mediate responses to these hormones have been the subject of intense research. This study dissected the hormonal cross talk regulating the synthesis of flavonols and examined their impact on root growth and development. We analyzed the effects of auxin and an ethylene precursor on roots of wild-type and hormone-insensitive Arabidopsis (Arabidopsis thaliana) mutants at the transcript, protein, and metabolite levels at high spatial and temporal resolution. Indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylic acid (ACC) differentially increased flavonol pathway transcripts and flavonol accumulation, altering the relative abundance of quercetin and kaempferol. The IAA, but not ACC, response is lost in the transport inhibitor response1 (tir1) auxin receptor mutant, while ACC responses, but not IAA responses, are lost in ethylene insensitive2 (ein2) and ethylene resistant1 (etr1) ethylene signaling mutants. A kinetic analysis identified increases in transcripts encoding the transcriptional regulators MYB12, Transparent Testa Glabra1, and Production of Anthocyanin Pigment after hormone treatments, which preceded increases in transcripts encoding flavonoid biosynthetic enzymes. In addition, myb12 mutants were insensitive to the effects of auxin and ethylene on flavonol metabolism. The equivalent phenotypes for transparent testa4 (tt4), which makes no flavonols, and tt7, which makes kaempferol but not quercetin, showed that quercetin derivatives are the inhibitors of basipetal root auxin transport, gravitropism, and elongation growth. Collectively, these experiments demonstrate that auxin and ethylene regulate flavonol biosynthesis through distinct signaling networks involving TIR1 and EIN2/ETR1, respectively, both of which converge on MYB12. This study also provides new evidence that quercetin is the flavonol that modulates basipetal auxin transport.

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Functional analysis of Arabidopsis genes involved in mitochondrial iron–sulfur cluster assembly

Cited by 52 publications

References 67 publications

The DUF59 Family Gene AE7 Acts in the Cytosolic Iron-Sulfur Cluster Assembly Pathway to Maintain Nuclear Genome Integrity in Arabidopsis

The DUF59 Family Gene AE7 Acts in the Cytosolic Iron-Sulfur Cluster Assembly Pathway to Maintain Nuclear Genome Integrity in Arabidopsis

The Essential Cytosolic Iron-Sulfur Protein Nbp35 Acts without Cfd1 Partner in the Green Lineage

Auxin and Ethylene Induce Flavonol Accumulation through Distinct Transcriptional Networks

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