Redox Modulation of Oligomeric State in Proline Utilization A
David A Korasick1, Ashley C Campbell1, Shelbi L Christgen2
1Department of Biochemistry, University of Missouri, Columbia, Missouri.
Biophysical Journal
|June 21, 2018
Summary
The active oligomeric state of Bradyrhizobium japonicum proline utilization A (PutA) depends on enzyme concentration and flavin cofactor redox state. This study reveals redox-linked oligomerization in the PutA family.
Area of Science:
- Biochemistry
- Enzymology
- Protein Structure
Background:
- Proline utilization A (PutA) bifunctional flavoenzymes' homooligomerization is crucial for catalytic function and substrate channeling.
- Bradyrhizobium japonicum PutA (BjPutA) uniquely forms a tetramer in solution, but a dimeric mutant showed wild-type activity, questioning its active oligomeric state.
Purpose of the Study:
- Investigate factors influencing BjPutA tetramerization in vitro.
- Determine the active oligomeric state of BjPutA.
Main Methods:
- Negative-stain electron microscopy to assess oligomeric state at low concentrations.
- Sedimentation-velocity analysis at high concentrations.
- Size-exclusion chromatography coupled with multiangle light scattering and small-angle X-ray scattering.
Main Results:
- BjPutA is primarily dimeric at nanomolar concentrations, indicating concentration-dependent tetramerization.
- At micromolar concentrations, active-site ligand binding does not affect oligomeric state.
- Reduction of the flavin adenine dinucleotide cofactor leads to a dimeric state, confirmed by multiple techniques.
- Redox-linked oligomerization is reported for the first time in the PutA family.
Conclusions:
- BjPutA's oligomeric state is regulated by both enzyme concentration and the redox state of its flavin cofactor.
- These findings challenge previous assumptions about PutA structure-function relationships and introduce the concept of redox-dependent oligomerization in this enzyme family.
Related Concept Videos
02:58Balancing Redox Equations
62.3K
Electrochemistry is the science involved in the interconversion of electrical and chemical reactions. Such reactions are called reduction-oxidation, or redox reactions. These important reactions are defined by changes in oxidation states for one or more reactant elements and include a subset of reactions involving the transfer of electrons between reactant species. Electrochemistry as a field has evolved to yield sufficient insights on the fundamental principles of redox chemistry and multiple...
62.3K
01:24Redox Reactions
58.9K
Oxidation-reduction or redox reactions involve the transfer of electrons from one molecule or atom to another. When an atom gains an electron, another atom must lose an electron, meaning oxidation and reduction must occur together. Since the redox occurs in pairs, the atom that gets oxidized is also called the reducing agent or reductant, and the atom that is reduced is also called the oxidizing agent or oxidant. A straightforward way to remember the definitions of oxidation and reduction is...
58.9K
01:27Redox Reactions
1.1K
Redox reactions are vital biochemical processes that underpin energy metabolism in cells. These reactions involve the transfer of electrons between molecules, occurring in tandem as oxidation and reduction. Oxidation refers to the loss of electrons, while reduction denotes their gain. This coupling ensures the seamless flow of electrons through metabolic pathways. For example, in bacterial metabolism, glucose undergoes oxidation to carbon dioxide, while oxygen is simultaneously reduced to...
1.1K
01:23Redox Equilibria: Overview
1.6K
A reduction-oxidation reaction is commonly called a redox reaction. In a redox reaction, electrons are transferred from one species to another rather than being shared between or among atoms. The reducing agent or reductant is the species that loses electrons and gets oxidized in the process. The species that gains electrons and gets reduced in the process is the oxidizing agent or oxidant. Redox reactions are represented as two separate equations called half-reactions, where one equation...
1.6K
01:21Redox Titration: Overview
5.0K
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...
5.0K
01:30Ladder Diagrams: Redox Equilibria
802
Ladder diagrams are useful tools for understanding redox equilibrium reactions, especially the effects of concentration changes on the electrochemical potential of the reaction. The vertical axis in the redox ladder diagrams represents the electrochemical potential, E. The area of predominance is demarcated using the Nernst equation.
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
802