Unraveling the molecular mechanism of polysaccharide lyases for efficient alginate degradation.

ABSTRACT: Alginate lyases (ALs) catalyze the depolymerization of brown macroalgae alginates, widely used naturally occurring polysaccharides. Their molecular reaction mechanism remains elusive due to the lack of catalytically competent Michaelis-Menten-like complex structures. Here, we provide structural snapshots and dissect the mechanism of mannuronan-specific ALs from family 7 polysaccharide lyases (PL7), employing time-resolved NMR, X-ray, neutron crystallography, and QM/MM simulations. We reveal the protonation state of critical active site residues, enabling atomic-level analysis of the reaction coordinate. Our approach reveals an endolytic and asynchronous syn β-elimination reaction, with Tyr serving as both Brønsted base and acid, involving a carbanion-type transition state. This study not o

SUBMITTER: Rivas-Fernandez JP 

PROVIDER: S-EPMC11920209 | biostudies-literature | 2025 Mar

REPOSITORIES: biostudies-literature