Src kinase conformational activation: thermodynamics, pathways, and mechanisms

Area of Science:

• Biochemistry
• Structural Biology
• Computational Biology

Background:

• Src-family tyrosine kinases are crucial allosteric enzymes in cellular signaling.
• Kinase activation involves significant conformational changes between inactive and active states.

Purpose of the Study:

• To model and simulate the dynamics of conformational transitions during Src kinase activation.
• To identify and characterize the energy landscapes and pathways governing kinase activation.

Main Methods:

• Construction of a coarse-grained model of the Src catalytic domain using experimental structures.
• Simulation of conformational transition dynamics.
• Analysis of transition energy landscapes via structural networks.
• Application of Markov models to study structural kinetics.

Main Results:

• Identification of two major ensembles of pathways for Src kinase activation.
• Characterization of a coordinated switching mechanism involving the alphaC helix, activation-loop, and N-lobe beta strands in one pathway.
• Observation of partial unfolding of the N-lobe in a second activation pathway.
• Detailed characterization of the alphaC helix and activation-loop switching mechanisms.

Conclusions:

• The study provides a framework for understanding Src kinase conformational transitions.
• Two distinct mechanisms, coordinated switching and N-lobe unfolding, drive Src activation.
• The findings offer insights into the allosteric regulation of Src-family tyrosine kinases.