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 uncharacterized. 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.