Abstract: Reproduction is a fundamental principle of biological systems, which is not found in chemistry or physics. The reproductive cells or primordial germ cells (PGCs) of many animal species are specified by a Ribonucleo-protein (RNP) granule termed germ plasm. So far, only two proteins are known to act as germ plasm organizers: Bucky ball (Buc) in zebrafish and Oskar (Osk) in Drosophila. Both proteins recapitulate germ plasm activities but seem to be unique to their animal groups. We discovered that Osk and Buc show conserved activities during germ cell specification. Overexpression of DrosophilaOsk in zebrafish induces additional PGCs. Surprisingly, Osk and Buc do not show homologous protein motifs that would explain their related function. Nonetheless, we detect that Osk and Buc contain long amino acid stretches of intrinsically disordered regions (IDRs). These IDRs rapidly change their sequence during evolution and hence, might obscure biochemical interaction motifs conserved between Osk and Buc. Indeed, we discover that Buc binds to the known Oskar interactors Vasa protein and nanosmRNA providing a molecular mechanism for their related function. These results identify a conserved core-complex in the germ plasm controlled by two proteins with unrelated sequence but similar activities. More importantly, Osk and Buc might represent a first example of a widespread phenomenon. Additional protein-pairs might exist in genome databases, which are currently listed as novel or species-specific, but with similar function across distant species.

1994-1999 PhD, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
1999-2003 Postdoc University of Pennsylvania, Philadelphia, USA
2004-2010 Junior group leader, University of Geneva, Switzerland
2010-2018 Group leader at the Inst. of Developmental Biochemistry, Georg August University, Göttingen
since 2018 Group leader at the Inst. of Human Genetics, University Medical Center, Göttingen