Activation loop dynamics are controlled by conformation-selective inhibitors of ERK2

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Protein kinases, such as mitogen-activated protein (MAP) kinase ERK2, play crucial roles in cellular signaling.
• ERK2 activation by dual phosphorylation induces global motions, shifting between inactive (L) and active (R) states.
• Small molecule inhibitors can exploit these conformational dynamics to modulate kinase activity.

Purpose of the Study:

• To investigate how ERK2 inhibitors Vertex-11e and SCH772984 interact with different conformational states of ERK2.
• To elucidate the structural and dynamic basis of selective inhibition.
• To understand how inhibitor binding affects ERK2 activity and regulation.

Main Methods:

• Nuclear magnetic resonance (NMR) spectroscopy to study protein dynamics.
• X-ray crystallography to determine protein-ligand complex structures.
• Hydrogen-exchange mass spectrometry (HX-MS) to probe protein-ligand interactions and conformational changes.

Main Results:

• Vertex-11e and SCH772984 shift the ERK2 L/R equilibrium in opposite directions.
• X-ray structures reveal inhibitor-induced conformational changes in ERK2, including domain closure and Gly-rich loop repositioning.
• HX-MS data show distinct binding modes and correlate protection with R-state formation, with differential effects on the activation loop.

Conclusions:

• ERK2 inhibitors exhibit conformational selection, targeting specific protein states.
• Global motions in ERK2 are coupled to active site conformational changes and activation loop dynamics.
• Conformationally selective inhibitors offer a mechanism to control kinase activity and dephosphorylation, expanding therapeutic possibilities.