Related Experiment Video
Updated: May 7, 2026
07:16
Resin-Assisted Capture Coupled with Isobaric Tandem Mass Tag Labeling for Multiplexed Quantification of Protein Thiol Oxidation
Published on: June 21, 2021
Monothiol glutaredoxins can bind linear [Fe3S4]+ and [Fe4S4]2+ clusters in addition to [Fe2S2]2+ clusters:
Bo Zhang1, Sibali Bandyopadhyay, Priyanka Shakamuri
1Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia , Athens, Georgia 30602, United States.
Journal of the American Chemical Society
|September 17, 2013
Summary
Saccharomyces cerevisiae mitochondrial glutaredoxin 5 (Grx5) predominantly contains a linear [Fe3S4](+) cluster, not just [Fe2S2](2+) clusters as previously thought. This finding impacts understanding of iron-sulfur cluster trafficking and protein maturation.
Area of Science:
- Biochemistry
- Bioinorganic Chemistry
- Molecular Biology
Background:
- Saccharomyces cerevisiae mitochondrial glutaredoxin 5 (Grx5) is a key monothiol glutaredoxin involved in iron-sulfur cluster trafficking.
- The CGFS active-site sequence is conserved in monothiol glutaredoxins, suggesting a common function in handling iron-sulfur clusters.
- Previous studies often interpreted the iron-sulfur cluster content in monothiol Grxs as [Fe2S2](2+) clusters.
Purpose of the Study:
- To characterize the iron-sulfur cluster composition of recombinant Saccharomyces cerevisiae Grx5.
- To investigate the structural and electronic properties of the iron-sulfur clusters bound to Grx5.
- To clarify the role of Grx5 in iron-sulfur cluster trafficking and protein maturation.
Main Methods:
- Purification of recombinant S. cerevisiae Grx5 under aerobic and anaerobic conditions.
- Spectroscopic characterization including UV-vis absorption/CD/MCD, EPR, Mössbauer, and resonance Raman spectroscopy.
- Mutational and analytical studies to assess cluster ligation.
Main Results:
- Recombinant Grx5 predominantly contains a linear [Fe3S4](+) cluster when purified aerobically or reconstituted anaerobically with glutathione.
- Spectroscopic data reveal a rhombic S = 5/2 linear [Fe3S4](+) cluster similar to synthetic analogs and purple aconitase.
- In the absence of glutathione, Grx5 forms a dimer with an [Fe4S4](2+) cluster, capable of in vitro apo-aconitase activation.
Conclusions:
- The iron-sulfur cluster content in monothiol Grxs, including Grx5, has been largely misinterpreted, with linear [Fe3S4](+) clusters being prevalent.
- Grx5 plays a role in scavenging and recycling linear [Fe3S4](+) clusters under oxidative stress and in the maturation of [Fe4S4](2+)-containing proteins.
Related Concept Videos
01:20Sulfur Assimilation
Sulfur is an essential element in biological systems, contributing to synthesizing key biomolecules, including amino acids such as cysteine and methionine, and cofactors such as coenzyme A and biotin. Microorganisms primarily assimilate sulfur as sulfate (SO₄²⁻) from the environment, which must undergo a series of biochemical transformations before it can be incorporated into cellular components. As sulfate is highly oxidized, it must undergo assimilatory sulfate reduction to become...
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
02:51Metal-Ligand Bonds
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
01:26Redox Titration: Other Oxidizing and Reducing Agents
Besides iodine, other oxidizing or reducing agents can serve as titrants in redox titrations. Common oxidizing titrants include KMnO4, cerium(IV), and K2Cr2O7. The choice of oxidizing titrants depends on factors like stability, cost, analyte strength, and reaction rate between the analyte and titrant. KMnO4 is a strong oxidizing titrant that reduces from Mn(VII) to Mn(II) in a highly acidic solution, simultaneously oxidizing the analyte to a higher oxidation state. In this case, KMnO4 acts as a...
01:21Redox Titration: Overview
Redox titration is a chemical analysis technique used to determine the concentration of an unknown substance by measuring the electron transfer in a redox (reduction-oxidation) reaction. The process involves gradually adding a titrant with a known concentration of an oxidizing or reducing agent, to the analyte, the solution with an unknown concentration, until reaching the endpoint, which indicates the completion of the reaction between the two substances. Ensuring the analyte is in a single...
00:43Complexometric Titration: Ligands
Different monodentate and polydentate ligands are used as complexing agents in complexometric titration reactions. The formation of complexes by mono- and bidentate ligands involves two or more intermediate steps, limiting their use as complexing agents. In comparison, polydentate ligands can form complexes with metal ions in a single-step process, facilitating sharper end points. This means polydentate ligands, such as amino carboxylic acid derivatives, are most commonly employed in...