Non-redundant cardiolipin synthase family proteins shape lipid composition and stress resilience in Bacteroides fragilis

ABSTRACT:

Gut-resident bacteria must withstand membrane-disrupting stresses such as bile acids to persist in the intestinal environment. The Bacteroidota are a dominant phylum of the human gut microbiota. However, the genes responsible for synthesis of membrane lipids in this phylum remain relatively uncharacterized. Bacteroides fragilis is a prevalent member of this phylum and encodes two predicted cardiolipin synthase family proteins, ClsA and ClsB. We previously identified both cls genes as bile-acid fitness factors in B. fragilis P207, but the contributions of clsA and clsB to cell physiology remained unclear. Here we combine targeted gene deletion with high-resolution lipidomics, metabolomics, and elemental mass spectrometry to show that ClsA and ClsB have distinct and non-redundant functions in the cell. Each cls gene makes a unique contribution to the lipid composition of B. fragilis and differs in its growth-phase expression pattern. Deletion of each gene produces distinct effects on cell morphology, fitness under membrane-perturbing stress, and the broader cellular metabolome, with clsA and clsB influencing levels of different glycyl-seryl peptidolipids, a Bacteroides lipid family that includes the TLR2-active flavolipin and that supports bile resistance and gut colonization. In contrast to the acute ion-gradient disruption caused by the secondary bile acid deoxycholate, deletion of clsA and clsB did not measurably alter steady-state intracellular ion levels under standard growth conditions. Together, these results define non-redundant roles for two cardiolipin synthase family proteins in a common member of the human gut microbiota.

INSTRUMENT(S): Liquid Chromatography MS - negative - reverse-phase, Liquid Chromatography MS - positive - reverse-phase

PROVIDER: MTBLS11891 | MetaboLights | 2026-10-06

REPOSITORIES: MetaboLights