Intrinsically disordered arginine-glycine repeat domains tune sub-nucleolar compartmentalization in Caenorhabditis elegans.

Intrinsically disordered arginine-glycine (RG) repeat domains are enriched in multilayered biomolecular condensates such as the nucleolus. Caenorhabditis elegans nucleolar RG repeats are dispensable for nucleolar accumulation and instead contribute to the organization of sub-nucleolar compartments. The sufficiency of RG repeats to facilitate sub-nucleolar compartmentalization is unclear. In this study, we drive expression of full-length RG repeats in the C. elegans germline to test their ability to localize to nucleoli and organize into nucleolar sub-compartments in vivo. We find that repeats accumulate within germ cell nucleoli but do not enrich in the correct sub-compartment. Our results suggest that RG repeats may indirectly influence nucleolar organization by creating an environment favorable for sub-nucleolar compartmentalization of proteins primarily based on their function within the nucleolus.