Ellinor Haglund

University of Hawaii, Manoa, USA - Research

Structural Plasticity in Chemokines Driven by Native and Non-Native Disulfide Bonds

Abstract

Disulfide bonds stabilize protein structure, guide folding, enable redox regulation, and create opportunities for functional and structural plasticity. While native disulfide bonds define the canonical functional fold of proteins, non-native disulfides can stabilize alternative conformational states that may modulate, alter, or even impair biological activity. The regulatory and pathological consequences of these alternative disulfide configurations remain poorly understood. In this work, we use the chemokine Interleukine-8 (IL-8) as our model system containing four cysteines forming two disulfide bonds. Chemokines are small, disulfide-rich signaling proteins that regulate immune cell trafficking through receptor activation and gradient formation. Conserved disulfide bonds stabilize the chemokine fold, yet alternative disulfide connectivities can arise under oxidative stress. A combination of molecular dynamics (MD) simulations with in vitro and in cell biological assays was used to understand the role of native versus non-native disulfides in IL-8. Our results show that native disulfide connectivity encodes structural precision beyond thermodynamic stability, fine-tuning core packing and conformational integrity to support proper chemokine function. By defining how alternative disulfide patterns reshape structure without globally destabilizing the fold, this work provides new mechanistic insight into disulfide-driven functional plasticity under physiological and oxidative stress conditions.