Co-option of lysosomal machinery shapes the evolution of the intracellular photosymbiosis supporting coral reefs.

Lysosomal proteins are co-opted to form the symbiosome, enabling photosymbiosis in corals and anemones, with the transporter SLC26A11 being essential for this process.

• Why it matters: Understanding how intracellular symbiosis evolves is crucial for insights into coral reef resilience and the development of new symbiotic systems, addressing gaps in molecular mechanisms behind repeated organelle evolution.
• What they did: Researchers analyzed the proteome of the symbiosome in Aiptasia, identified lysosomal protein enrichment, visualized lysosomal fusion, and used CRISPR/Cas9 to demonstrate that the lysosomal transporter SLC26A11 is necessary for maintaining symbiosis.
• The result: Findings show that co-opting lysosomal machinery facilitates metabolite exchange and carbon concentration, providing a straightforward evolutionary pathway for the repeated emergence of photosymbiosis in corals and anemones.