TY - JOUR TI - A contractile injection system stimulates tubeworm metamorphosis by translocating a proteinaceous effector AU - Ericson, Charles F AU - Eisenstein, Fabian AU - Medeiros, João M AU - Malter, Kyle E AU - Cavalcanti, Giselle S AU - Zeller, Robert W AU - Newman, Dianne K AU - Pilhofer, Martin AU - Shikuma, Nicholas J A2 - Kudryashev, Misha A2 - Storz, Gisela VL - 8 PY - 2019 DA - 2019/09/17 SP - e46845 C1 - eLife 2019;8:e46845 DO - 10.7554/eLife.46845 UR - https://doi.org/10.7554/eLife.46845 AB - The swimming larvae of many marine animals identify a location on the sea floor to undergo metamorphosis based on the presence of specific bacteria. Although this microbe–animal interaction is critical for the life cycles of diverse marine animals, what types of biochemical cues from bacteria that induce metamorphosis has been a mystery. Metamorphosis of larvae of the tubeworm Hydroides elegans is induced by arrays of phage tail-like contractile injection systems, which are released by the bacterium Pseudoalteromonas luteoviolacea. Here we identify the novel effector protein Mif1. By cryo-electron tomography imaging and functional assays, we observe Mif1 as cargo inside the tube lumen of the contractile injection system and show that the mif1 gene is required for inducing metamorphosis. Purified Mif1 is sufficient for triggering metamorphosis when electroporated into tubeworm larvae. Our results indicate that the delivery of protein effectors by contractile injection systems may orchestrate microbe–animal interactions in diverse contexts. KW - contractile injection system KW - metamorphosis KW - symbiosis KW - phage KW - T6SS KW - development JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -