title: Germ plasm localisation of the HELICc of Vasa in Drosophila: analysis of domain sufficiency and amino acids critical for localisation.
abstract: Formation of the germ plasm drives germline specification in Drosophila and some other insects such as aphids. Identification of the DEAD-box protein Vasa (Vas) as a conserved germline marker in flies and aphids suggests that they share common components for assembling the germ plasm. However, to which extent the assembly order is conserved and the correlation between functions and sequences of Vas remain unclear. Ectopic expression of the pea aphid Vas (ApVas1) in Drosophila did not drive its localisation to the germ plasm, but ApVas1 with a replaced C-terminal domain (HELICc) of Drosophila Vas (DmVas) became germ-plasm restricted. We found that HELICc itself, through the interaction with Oskar (Osk), was sufficient for germ-plasm localisation. Similarly, HELICc of the grasshopper Vas could be recruited to the germ plasm in Drosophila. Nonetheless, germ-plasm localisation was not seen in the Drosophila oocytes expressing HELICcs of Vas orthologues from aphids, crickets, and mice. We further identified that glutamine (Gln) 527 within HELICc of DmVas was critical for localisation, and its corresponding residue could also be detected in grasshopper Vas yet missing in the other three species. This suggests that Gln527 is a direct target of Osk or critical to the maintenance of HELICc conformation.
authors.affiliation: Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan.
authors.forename: Szu-Chieh
authors.initials: SC
authors.lastname: Wang
authors.affiliation: Department of Life Science, Tzu-Chi University, Hualien, Taiwan.
authors.forename: Hao-Jen
authors.initials: HJ
authors.lastname: Hsu
authors.affiliation: Laboratory for Genetics and Development, Department of Entomology/Institute of Biotechnology, College of Bioresources and Agriculture, National Taiwan University, Taipei, Taiwan.|Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan.
authors.forename: Gee-way
authors.initials: GW
authors.lastname: Lin
authors.affiliation: Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan.
authors.forename: Ting-Fang
authors.initials: TF
authors.lastname: Wang
authors.affiliation: Laboratory for Genetics and Development, Department of Entomology/Institute of Biotechnology, College of Bioresources and Agriculture, National Taiwan University, Taipei, Taiwan.|Research Center for Developmental Biology and Regenerative Medicine, National Taiwan University, Taipei, Taiwan.|Genome and Systems Biology Degree Program, National Taiwan University and Academia Sinica, Taipei, Taiwan.
authors.forename: Chun-che
authors.initials: CC
authors.lastname: Chang
authors.affiliation: Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan.|Department of Life Science, Tzu-Chi University, Hualien, Taiwan.
authors.forename: Ming-Der
authors.initials: MD
authors.lastname: Lin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003593:Cytoplasm; D053487:DEAD-box RNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000066630:Ectopic Gene Expression; D005854:Germ Cells / Q000378:metabolism*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D021381:Protein Transport; D016415:Sequence Alignment
chemical_list: D029721:Drosophila Proteins; C088269:vas protein, Drosophila; D053487:DEAD-box RNA Helicases