Abstract
The sulfhydryl oxidase Erv1 partners with the oxidoreductase Mia40 to import cysteine-rich proteins in the mitochondrial intermembrane space. In Saccharomyces cerevisiae, Erv1 has also been implicated in cytosolic Fe-S protein maturation and iron regulation. To investigate the connection between Erv1/Mia40-dependent mitochondrial protein import and cytosolic Fe-S cluster assembly, we measured Mia40 oxidation and Fe-S enzyme activities in several erv1 and mia40 mutants. Although all the erv1 and mia40 mutants exhibited defects in Mia40 oxidation, only one erv1 mutant strain (erv1-1) had significantly decreased activities of cytosolic Fe-S enzymes. Further analysis of erv1-1 revealed that it had strongly decreased glutathione (GSH) levels, caused by an additional mutation in the gene encoding the glutathione biosynthesis enzyme glutamate cysteine ligase (GSH1). To address whether Erv1 or Mia40 plays a role in iron regulation, we measured iron-dependent expression of Aft1/2-regulated genes and mitochondrial iron accumulation in erv1 and mia40 strains. The only strain to exhibit iron misregulation is the GSH-deficient erv1-1 strain, which is rescued with addition of GSH. Together, these results confirm that GSH is critical for cytosolic Fe-S protein biogenesis and iron regulation, whereas ruling out significant roles for Erv1 or Mia40 in these pathways.
Highlights
The mitochondrial sulfhydryl oxidase Erv1 is implicated in cytosolic iron-sulfur protein maturation and iron regulation
We found that the erv1-1 strain had dramatically depleted GSH levels in both the mitochondria and cytosol, whereas GSH levels were normal in other erv1 and mia40 mutants
The temperature-sensitive erv1 strain, named erv1-1, was first described by Lisowsky [19, 35], and shown to exhibit defects in intermembrane space (IMS) protein import [4] and maturation of cytosolic Fe-S clusters [7]. This strain harbors an Erv1 F124S mutation located at the dimer interface [36] and likely impairs Erv1 dimerization, which is essential for catalytic function [22]
Summary
The mitochondrial sulfhydryl oxidase Erv is implicated in cytosolic iron-sulfur protein maturation and iron regulation. Results: An erv yeast strain used in previous iron metabolism studies is glutathione-deficient, and erv1/mia mutants with sufficient glutathione do not exhibit iron-related defects. To investigate the connection between Erv1/ Mia40-dependent mitochondrial protein import and cytosolic Fe-S cluster assembly, we measured Mia oxidation and Fe-S enzyme activities in several erv and mia mutants. The only strain to exhibit iron misregulation is the GSH-deficient erv strain, which is rescued with addition of GSH. Together, these results confirm that GSH is critical for cytosolic Fe-S protein biogenesis and iron regulation, whereas ruling out significant roles for Erv or Mia in these pathways
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
