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Title: The mitochondrial-cytosolic pathway of FeS cluster assembly in Arabidopsis thaliana
Author: Kruse, Inga
ISNI:       0000 0004 6058 8459
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2016
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The aim of this work was to unravel the molecular basis of the connection of mitochondrial and cytosolic FeS assembly. Following on from previous work showing that the mitochondrial ABC-transporter ATM3 is required for cytosolic FeS assembly (Bernard et al., 2009), one part of my project was to provide in-vivo evidence for the substrate of ATM3. I found that the mitochondrial glutathione pool in atm3 seedlings is shifted towards oxidation, indicating accumulation of oxidised glutathione. Furthermore I showed that ATM3 genetically interacts with two enzymes involved in persulfide metabolism (ETHE1, NFS1). This complemented invitro studies by Dr. Schaedler (Schaedler et al., 2014) who showed that oxidised glutathione is a preferred substrate and glutathione carrying additional S0 can be transported by yeast Atm1. To gather further insight into biosynthesis of the ATM3 substrate I investigated the role of a cytosolic and a mitochondrial glutaredoxin (GRXS17, GRXS15). Mutants had minor but specific effects on FeS enzymes and I concluded that the glutaredoxins are not generally involved in de-novo cluster assembly. Another approach was to identify unknown components of mitochondrial-cytosolic persulfide transport. I characterised two mutants with phenotypic resemblance to atm3 mutants. For one, I located a point mutation in the sequence of ATM3 leading to an amino acid exchange in the 6th transmembrane domain and showed that the ATM3 protein was lacking. The second line was a mutant of CNX2, a mitochondrial enzyme necessary for generation of the first MoCo intermediate cPMP. I found ATM3 protein breakdown in cnx2-2 and in a mutant of CNX5 which is involved in MoCo assembly and t-RNA thiomodification. ATM3 was previously suggested to export cPMP (Teschner et al., 2010). My findings give new evidence for a link between ATM3 and MoCo assembly.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available