Activation Loop Plasticity and Active Site Coupling in the MAP Kinase, ERK2

Area of Science:

• Molecular Biology
• Biochemistry
• Computational Biology

Background:

• Previous studies indicated ERK2 dynamics change upon phosphorylation-induced activation.
• Understanding the specific conformational motions involved in ERK2 activation remains incomplete.

Purpose of the Study:

• To investigate the conformational dynamics of ERK2 using extensive molecular dynamics simulations.
• To elucidate the role of the A-loop in ERK2 regulation and its coupling with active site dynamics.

Main Methods:

• Conducted long conventional molecular dynamics (MD) simulations (totaling 727 μs) of phosphorylated (2P) and unphosphorylated (0P) ERK2.
• Utilized differential contact network and principal component analyses to assess protein dynamics and conformational states.

Main Results:

• Identified multiple long-lived conformational states (>5 μs) of the ERK2 A-loop in both 2P- and 0P-forms.
• Revealed coupling between A-loop conformation and active site dynamics, with evidence of conformational selection in 2P-ERK2.
• Observed distinct A-loop behaviors: restrained dynamics in 2P-ERK2 (N-lobe interactions) versus increased mobility in 0P-ERK2 (C-lobe excursions).

Conclusions:

• The ERK2 A-loop dynamically switches conformations, directly influencing active site dynamics and kinase regulation.
• Phosphorylation-dependent A-loop conformations modulate active site compaction and catalytic residue accessibility.
• MD simulations reveal novel conformational states, enhancing the understanding of ERK2 activation mechanisms.