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Publication Abstract from PubMed

Shotgun metagenomic sequencing has emerged as a powerful tool for exploring microbial diversity and uncovering genes encoding novel biocatalysts from complex environments. Here, we report the discovery and characterization of a new FAD-dependent D-lactate dehydrogenase (PdG-D-LDH) from the gut microbiome of the isopod Porcellio dilatatus. The enzyme was identified through in silico screening using BLAST and AlphaFold3 and functionally characterized as a homodimeric, thermoactive, and thermostable protein, demonstrating the robustness required for biotechnological applications. PdG-D-LDH exhibits a strong catalytic preference toward D-lactate and preferentially reduces quinones over cytochrome c or molecular oxygen. X-ray crystallography revealed a VAO/PCMH-like fold with a solvent-accessible active site that harbors both a FAD cofactor and an Fe(II) ion. Molecular docking studies provided insights into the structural determinants of its stereoselective substrate recognition. Under mild conditions, the enzyme catalyzed the oxidation of D-lactate to pyruvate with a 90% yield after 24 h of reaction, using molecular oxygen as the electron acceptor. IMPORTANCE: This study illustrates how metagenomics, structural biology, and computational tools can jointly drive the discovery of new enzymes with valuable biotechnological applications aligned with circular economic principles. The newly identified D-lactate dehydrogenase, PdG-D-LDH, exhibits thermostability, stereoselectivity, and high catalytic efficiency, providing new insights into the structure-function relationships of lactate-metabolizing enzymes.

Shotgun metagenomic mining reveals a new FAD-dependent D-lactate dehydrogenase in an isopod gut microbiome.,Coelho C, Taborda A, Lorena C, Frazao T, Verissimo A, Borges PT, Brissos V, Tiago I, Martins LO Appl Environ Microbiol. 2025 Nov 13:e0148025. doi: 10.1128/aem.01480-25. PMID:41231970^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.