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

Abstract

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.

Requirements of the cytosolic iron–sulfur cluster assembly pathway in Arabidopsis

“…It has been shown that AtTAH18, AtNBP35, AtNAR1, AtCIA1 and one of the AtCIA2 genes (named AE7) are each essential for embryo development (see table 1 and references). In contrast, Arabidopsis met18 knock-out mutants have no obvious phenotype [37].…”

“…Although the precise molecular functions of these proteins remain to be determined, the formation of the complex and its biological function is conserved from yeast to humans and plants [37,48,49]. A universal phenotype of cia mutants is the loss of nuclear genome integrity.…”

Role of the Porphyromonas gingivalis iron-binding protein PG1777 in oxidative stress resistance

“…Although this domain has been identified in a wide array of proteins, and may have several functions, there is a family of ORFs that are part of a conserved chromosomal group of proteins predicted to be involved in iron-sulfur cluster metabolism (Almeida et al, 2005). Of the four published studies on proteins with DUF59 domain at the time of this submission, two have demonstrated the involvement of proteins with these domains in iron-sulfur cluster assembly (Chen et al, 2012;Luo et al, 2012).…”

“…A small 105 aa protein, PG1777, has been shown to possess a domain of unknown function, DUF59 (www.ncbi.nlm.nih.gov), which has been identified in several bacteria and eukaryotes (Almeida et al, 2005;Chen et al, 2012;Luo et al, 2012). Although this domain has been identified in a wide array of proteins, and may have several functions, there is a family of ORFs that are part of a conserved chromosomal group of proteins predicted to be involved in iron-sulfur cluster metabolism (Almeida et al, 2005).…”

The Opposing Actions of Arabidopsis CHROMOSOME TRANSMISSION FIDELITY7 and WINGS APART-LIKE1 and 2 Differ in Mitotic and Meiotic Cells

“…This assay has been used in Arabidopsis as a reliable method to quantify DNA repair kinetics in response to chemical and environmental agents that cause DNA damage (Luo et al, 2012;Nezames et al, 2012). The assay is prone to saturation and requires prior calibration of doses and the careful standardization of experimental conditions to maintain background DNA damage at a minimum (Collins et al, 2008).…”