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Published on: March 10, 2023
Kinetic network model to explain gain-of-function mutations in ERK2 enzyme
Mikita Misiura1, Anatoly B Kolomeisky1
1Department of Chemistry, Rice University, Houston, Texas 77005-1892, USA.
Abstract:
ERK2 is a kinase protein that belongs to a Ras/Raf/MEK/ERK signaling pathway, which is activated in response to a range of extracellular signals. Malfunctioning of this cascade leads to a variety of serious diseases, including cancers. This is often caused by mutations in proteins belonging to the cascade, frequently leading to abnormally high activity of the cascade even in the absence of an external signal. One such "gain-of-function" mutation in the ERK2 protein, called a "sevenmaker" mutation (D319N), was discovered in 1994 in Drosophila. The mutation leads to disruption of interactions of other proteins with the D-site of ERK2 and results, contrary to expectations, in an increase of its activity in vivo. However, no molecular mechanism to explain this effect has been presented so far. The difficulty is that this mutation should equally negatively affect interactions of ERK2 with all substrates, activators, and deactivators. In this paper, we present a semiquantitative kinetic network model that gives a possible explanation of the increased activity of mutant ERK2 species. A simplified biochemical network for ERK2, viewed as a system of coupled Michaelis-Menten processes, is presented. Its dynamic properties are calculated explicitly using the method of first-passage processes. The effect of mutation is associated with changes in the strength of interaction energy between the enzyme and the substrates. It is found that the dependence of kinetic properties of the protein on the interaction energy is nonmonotonic, suggesting that some mutations might lead to more efficient catalytic properties, despite weakening intermolecular interactions. Our theoretical predictions agree with experimental observations for the sevenmaker mutation in ERK2. It is also argued that the effect of mutations might depend on the concentrations of substrates.
Insights
A "sevenmaker" mutation in ERK2 protein kinase enhances its activity by altering enzyme-substrate interactions. This study models how weakened interactions can paradoxically boost catalytic efficiency, explaining disease-linked pathway overactivation.
Area of Science:
- Biochemistry and Molecular Biology
- Systems Biology
- Enzyme Kinetics
Background:
- The Ras/Raf/MEK/ERK signaling pathway is crucial for cellular responses but its dysregulation, often due to mutations, drives diseases like cancer.
- The ERK2 (Extracellular signal-regulated kinase 2) protein is a key component of this pathway, and specific mutations can lead to its hyperactivation.
- A known "gain-of-function" mutation in ERK2, the "sevenmaker" mutation (D319N), increases its activity in vivo, but the underlying molecular mechanism remains unclear.
Purpose of the Study:
- To elucidate the molecular mechanism behind the increased activity of the ERK2 "sevenmaker" mutant.
- To develop a theoretical model explaining how a mutation can paradoxically enhance enzyme activity despite disrupting interactions.
- To investigate the relationship between enzyme-substrate interaction energy and catalytic efficiency in ERK2.
Main Methods:
- Development of a semiquantitative kinetic network model for ERK2, treating it as a system of coupled Michaelis-Menten processes.
- Utilized the method of first-passage processes to calculate the dynamic properties of the ERK2 biochemical network.
- Analyzed the impact of altered interaction energy between ERK2 and its substrates on kinetic properties.
Main Results:
- The study presents a model where the "sevenmaker" mutation's effect is linked to changes in enzyme-substrate interaction energy.
- Demonstrated a nonmonotonic dependence of ERK2 kinetic properties on interaction energy, suggesting that weakened interactions can sometimes enhance catalytic efficiency.
- Theoretical predictions from the model align with experimental observations of the "sevenmaker" mutation's effect on ERK2 activity.
Conclusions:
- The increased activity of the ERK2 "sevenmaker" mutant can be explained by changes in enzyme-substrate interaction energy, leading to enhanced catalytic properties.
- This work highlights that mutations weakening intermolecular interactions may paradoxically improve enzyme function.
- The study suggests that substrate concentrations might also influence the effect of mutations on enzyme activity.
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