Network reorganization of a cold-adapted β-glucosidase couples conformational flexibility to catalytic efficiency under low-temperature conditions.

Introduction: Elucidating how cold-active enzymes maintain efficient catalysis under low-temperature conditions remains a significant question in enzymology. Although enhanced conformational flexibility has been frequently associated with cold adaptation, flexibility alone cannot fully explain how catalytic precision and reproducibility are maintained. This suggests that an additional layer of structural organization is required. Methods: In this study, a psychrophilic β-glucosidase (pBGL) from Pseudoalteromonas sp. BSw20308 and its mutant variant pBGL-S306P were examined through biochemical assays, molecular dynamics simulations, and dynamic interaction network analysis. Results: The results indicate that pBGL preserves high catalytic efficiency at low temperature despite pronounced thermal instability, maintaining a rigid and conserved catalytic core. Notably, increased flexibility is spatially redistributed toward peripheral and interfacial regions rather than being globally amplified. Network analysis reveals that cold adaptation is associated with a distributed interaction network that connects these flexible regions to the catalytic core, constraining motions into coordinated dynamics that support catalysis. Discussion: These findings suggest that cold adaptation in pBGL may involve not only enhanced flexibility but also network-mediated organization of conformational dynamics, providing a structural framework for understanding the activity-stability balance of cold-active enzymes.