Novel LOTUS-domain proteins are organizational hubs that recruit C. elegans Vasa to germ granules
Patricia G. Cipriani, Olivia Bay, John Zinno, Michelle Gutwein, Hin Hark Gan, Vinay K. Mayya, George Chung, Jia‐Xuan Chen, Hala Fahs, Yu Guan, Thomas F. Duchaîne, Matthias Selbach, Fabio Piano, Kristin C. Gunsalus
Abstract
germ granule components that interact with the intrinsically disordered MEG-3 protein. These proteins promote P granule condensation, form granules independently of MEG-3 in the postembryonic germ line, and balance each other in regulating P granule growth and localization. MIP-1 and MIP-2 each contain two LOTUS domains and intrinsically disordered regions and form homo- and heterodimers. They bind and anchor the Vasa homolog GLH-1 within P granules and are jointly required for coalescence of MEG-3, GLH-1, and PGL proteins. Animals lacking MIP-1 and MIP-2 show temperature-sensitive embryonic lethality, sterility, and mortal germ lines. Germline phenotypes include defects in stem cell self-renewal, meiotic progression, and gamete differentiation. We propose that these proteins serve as scaffolds and organizing centers for ribonucleoprotein networks within P granules that help recruit and balance essential RNA processing machinery to regulate key developmental transitions in the germ line.