Recombinant expression of single eukaryotic-like proteins changes bacteria-sponge interactions

Eukaryotic-like proteins (ELP) are often found in intracellular symbionts of insects, plants and evolutionary early-branching sponges, however their functions remain largely uncharacterised. Here we show that the recombinant expression of single genes of various ELP classes can confer on free-living cyanobacteria the capacity to escape phagocytosis by sponges and thus enable intracellular survival. The findings establish ELPs as molecular factors that can control sponge-microbe interactions, which has implications for the evolution of microbial symbiosis.