The mitochondrial-cytosolic pathway of FeS cluster assembly in Arabidopsis thaliana

Kruse, Inga (2016) The mitochondrial-cytosolic pathway of FeS cluster assembly in Arabidopsis thaliana. Doctoral thesis, University of East Anglia.

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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.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Jackie Webb
Date Deposited: 09 Mar 2017 11:43
Last Modified: 09 Mar 2017 11:43


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