An RNA-Binding Multimer Specifies Nematode Sperm Fate.
Aoki, S.T., Porter, D.F., Prasad, A., Wickens, M., Bingman, C.A., Kimble, J.(2018) Cell Rep 23: 3769-3775
- PubMed: 29949762 
- DOI: https://doi.org/10.1016/j.celrep.2018.05.095
- Primary Citation of Related Structures:  
5TD6 - PubMed Abstract: 
FOG-3 is a master regulator of sperm fate in Caenorhabditis elegans and homologous to Tob/BTG proteins, which in mammals are monomeric adaptors that recruit enzymes to RNA binding proteins. Here, we determine the FOG-3 crystal structure and in vitro demonstrate that FOG-3 forms dimers that can multimerize. The FOG-3 multimeric structure has a basic surface potential, suggestive of binding nucleic acid. Consistent with that prediction, FOG-3 binds directly to nearly 1,000 RNAs in nematode spermatogenic germ cells. Most binding is to the 3' UTR, and most targets (94%) are oogenic mRNAs, even though assayed in spermatogenic cells. When tethered to a reporter mRNA, FOG-3 represses its expression. Together these findings elucidate the molecular mechanism of sperm fate specification and reveal the evolution of a protein from monomeric to multimeric form with acquisition of a distinct mode of mRNA repression.
Organizational Affiliation: 
Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.