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Related Experiment Video

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Anaerobic Protein Purification and Kinetic Analysis via Oxygen Electrode for Studying DesB Dioxygenase Activity and Inhibition

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Activation by substoichiometric inhibition.

Melisa Merdanovic¹, Steven G Burston², Anna Laura Schmitz¹

¹Center of Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, 45117 Essen, Germany.

Proceedings of the National Academy of Sciences of the United States of America

|January 8, 2020

Summary

Drug inhibitors can paradoxically activate target proteins like BRAF V600E, especially at low doses. This "activation by inhibition" phenomenon, explained by allostery and cooperativity, has significant implications for drug development strategies.

Keywords:

HTRA1 HtrA proteases allostery cooperativity inhibitor

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Area of Science:

Biochemistry
Molecular Biology
Pharmacology

Background:

Paradoxical activation of the mitogen-activated protein kinase pathway by BRAF V600E inhibitors has been reported.
This phenomenon occurs when inhibitors target mutated BRAF (V600E) but not wild-type (wt-BRAF).

Purpose of the Study:

To conceptually analyze the general phenomenon of "activation by inhibition" using biochemical principles.
To explain the paradoxical activation observed with BRAF V600E inhibitors.

Main Methods:

Utilized bacterial and human HtrA proteases as model systems.
Performed a conceptual analysis based on allostery and cooperativity principles.

Main Results:

Substoichiometric inhibitor occupancy leads to partial inhibition but is overridden by activation of unliganded sites.
Cooperative enzymes can be activated rather than inhibited when inhibitor levels are not saturating.

Conclusions:

"Activation by inhibition" is explained by allosteric and cooperative binding mechanisms.
Non-saturating drug concentrations can lead to unintended activation of target enzymes, impacting drug efficacy.
Findings have critical implications for optimizing drug development and administration strategies.