Secreted SyeA protein enables Buchnera colonization of aphid embryos
Researchers identify SyeA, a secreted Buchnera protein that is dispatched into the aphid embryonic cytoplasm and is essential for Buchnera transmission to developing embryos. Structural analyses link SyeA to pathogen effectors (EspG/VirA) and suggest it may interact with host actin regulators (Rho1), coordinating cytoskeletal changes and lysosome trafficking to enable intracellular colonization. Antisense PNA knockdown reduces syeA expression, disrupts embryo colonization, leads to malformed embryos, and increases lysosomal degradation of Buchnera, highlighting SyeA as a vestige of bacterial invasion that evolved into a critical mutualist function.