Fig. 3: Osedax and its endosymbiont reconstruct the glyoxylate cycle.

a Circular schematic representation of the genome of Osedax endosymbiont Rs1, assembled into a single contig. The plot shows the genomic location of genes involved in amino acid, lipid and vitamin/cofactor metabolism (in orange, blue and red, respectively) and the GC content (inner circle; brown colour). b Oceanospirillales endosymbionts possess the glyoxylate cycle, a metabolic pathway that can produce oxaloacetate, which can serve as the precursor to synthesise carbohydrates from the oxidation of fatty acids. This metabolic pathway could thus contribute to synthesising glucose in a diet (the bone) that is naturally poor in carbohydrates. Notably, this molecular and metabolic interaction does not occur between Vestimentifera and its symbionts because the host and microbes lack the enzyme isocitrate lyase.