Functional divergence caused by mutations in an energetic hotspot in ERK2

Area of Science:

• Molecular Biology
• Cell Signaling
• Biochemistry

Background:

• The extracellular signal-regulated kinase 2 (ERK2) E322K mutation is common in cancers and affects the docking (CD) site, impacting cellular responses and drug resistance.
• While ERK2 E322K increases cellular activity and evades phosphatase inactivation, its precise cellular consequences remain unclear.

Purpose of the Study:

• To investigate the cellular and structural consequences of the ERK2 E322K mutation and compare them to the ERK2 D321N (sevenmaker) mutation.
• To elucidate the functional differences between these contiguous CD site mutations and their impact on ERK2 activity and stability.

Main Methods:

• Comparative analysis of ERK2 E322K and ERK2 D321N mutations in cancer cells and developmental assays.
• Crystal structure determination of ERK2 mutants.
• Assessment of thermal stability and phosphatase evasion.

Main Results:

• ERK2 E322K causes significant structural changes, including CD site disorder and activation loop exposure, leading to decreased thermal stability.
• ERK2 D321N shows increased activity and thermal stability, with a crystal structure indistinguishable from wild-type ERK2.
• In *Drosophila* developmental assays, only ERK2 D321N displayed a significant gain of function, indicating mutation-specific phenotypes.

Conclusions:

• The ERK2 CD site is under energetic strain, influencing distal conformational changes during docking.
• Contiguous mutations within the ERK2 CD site can lead to unpredictably different functional outcomes and structural consequences.
• Understanding these mutation-specific effects is crucial for targeted cancer therapies and comprehending kinase regulation.