[2S01a] 10. ASPIRE - Part 5

2:15 PM - 2:45 PM JST(5:15 AM - 5:45 AM UTC)

[2ASPR-10] Minimal Perturbation of ActivationLoop Dynamics Rewires Kinase Signaling

○Paola Laurino¹ (1. Okinawa Institute of Science and Technology Grad Univ (Japan))

Keywords:

Protein engineering,protein evolution,cellular signalling

Minimal mutations can dramatically reshape protein function, driving evolutionary innovation in unexpected ways. Changes occurring in flexible regions—such as loops and hinges—are often particularly impactful, as they modulate protein dynamics rather than static structure. These regions are also highly sensitive to the cellular environment, where physical and chemical constraints further shape protein behavior.In this talk, I will present a case study from our laboratory illustrating how subtle perturbations of protein dynamics can reprogram enzymatic function. Focusing on SRC kinase, a central signaling hub whose activity is governed by a regulatory activation loop, we dissect how loop dynamics encode substrate specificity, catalytic efficiency, and downstream signaling output. By generating and characterizing a series of activation-loop variants, we identified a minimal triple-deletion mutant that alters loop conformational sampling. Structural and biochemical analyses revealed distinct dynamic states associated with a shift in substrate preference toward more acidic motifs. These fine-tuned conformational changes translate into specific cellular signaling outcomes, as demonstrated by phosphoproteomic profiling. Comparative analysis across species further shows that evolution exploits similar loop remodeling strategies to modulate kinase function.Together, these results highlight how small, localized changes in flexible protein regions can have system-level consequences, offering a general framework for understanding protein evolution and for rationally rewiring signaling pathways in diverse cellular contexts.