PUF partner interactions at a conserved interface shape the RNA-binding landscape and cell fate in Caenorhabditis elegans

Protein-RNA regulatory networks underpin much of biology. C. elegans FBF-2, a PUF-RNA-binding protein, binds over 1,000 RNAs to govern stem cells and differentiation. FBF-2 interacts with multiple protein partners via a key tyrosine, Y479. Here, we investigate the in vivo significance of partnerships using a Y479A mutant. Occupancy of the Y479A mutant protein increases or decreases at specific sites across the transcriptome, varying with RNAs. Germline development also changes in a specific fashion: Y479A abolishes one FBF-2 function-the sperm-to-oocyte cell fate switch. Y479A's effects on the regulation of one mRNA, gld-1, are critical to this fate change, though other network changes are also important. FBF-2 switches from repression to activation of gld-1 RNA, likely by distinct FBF-2 partnerships. The role of RNA-binding protein partnerships in governing RNA regulatory networks will likely extend broadly, as such partnerships pervade RNA controls in virtually all metazoan tissues and species.