Binding of in vitro reconstituted snR30 Ribonucleoprotein to Ribosomal RNA

The creation of eukaryotic ribosomes is a complex process involving hundreds of assembly factors, including the small nucleolar RNA snR30. Through interacting with the unprocessed precursor ribosomal RNA (pre-rRNA), snR30 is essential for the maturation of pre-rRNA forming the small ribosomal subunit. To characterize snR30’s interaction network, an in vitro approach was used to quantify the affinity of snR30 to the core H/ACA protein complex and the PIN endonuclease Utp23 revealing very tight interactions with affinities in the sub- and low-nanomolar ranges, respectively. Furthermore, the snR30 complex binds tightly to its primary binding site in ribosomal RNA called the C1 site, but only weakly to other predicted interaction sites. Utp23 binds tightly to its predicted interaction site in ribosomal RNA only if adjacent rRNA elements are also present. In conclusion, these findings serve as foundational work to further explore the mechanisms of snR30 during maturation of rRNA.