OB or Not OB: Idiosyncratic utilization of the tRNA-binding OB-fold domain in unicellular, pathogenic eukaryotes

In this review, we examine the so-called OB-fold, a tRNA-binding domain homologous to the bacterial tRNA-binding protein Trbp111. We highlight the ability of OB-fold homologs to bind tRNA species and summarize their distribution in evolution. Nature has capitalized on the advantageous effects acquired when an OB-fold domain binds to tRNA by evolutionarily selecting this domain for fusion to different enzymes. Here, we review our current understanding of how the complexity of OB-fold-containing proteins and enzymes developed to expand their functions, especially in unicellular, pathogenic eukaryotes.