Giant viruses encode vitamin K-based redox modules for lipid modification.

Authors

Rebecca Collins, Julien Andréani, Dariana Annet Chavez, Douglas Brandt Rusch, Dana Boyd, Philippe Colson, Bernard La Scola, Cristina Landeta

Published in

Proceedings of the National Academy of Sciences of the United States of America. Volume 123. Issue 33. Pages e2610764123. Aug 18, 2026. Epub Aug 10, 2026.

Abstract

Viruses with large DNA genomes often carry auxiliary metabolic genes that reprogram host physiology, yet their contributions to host redox and membrane homeostasis remain poorly understood. Here, we report the finding and functional reconstitution of viral homologs of vitamin K epoxide reductase (VKOR) encoded by giant viruses. Using phylogenetic and genomic context analysis, we find that viral VKOR genes are frequently located adjacent to γ-carboxylase-like epoxidase and fatty acid desaturase domains, consistent with a putative modular redox pathway for membrane lipid modification. To investigate their function, we expressed viral VKORs in an Escherichia coli strain lacking disulfide bond-forming enzymes and examined both their membrane topology and activity. Remarkably, a minimal set of residue substitutions enabled proper membrane insertion and restored bacterial motility, demonstrating that viral VKORs are catalytically competent electron shuttles. Structural modeling supports their integration into the endoplasmic reticulum-like environment in the host. Finally, we show that VKORs and γ-carboxylase-like epoxidase-desaturases from Fadolivirus and Yasminevirus giant viruses are expressed during infection of Vermamoeba vermiformis, where they may couple vitamin K epoxidation to desaturation-driven lipid remodeling. These findings expand the known functional repertoire of giant viruses and highlight a viral strategy for manipulating host redox metabolism and membrane composition.

PMID:
42574618
Bibliographic data and abstract were imported from PubMed on 11 Aug 2026.

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