2'-O-methylation on rRNA of Trypanosoma brucei is developmentally regulated

The parasite Trypanosoma brucei cycles between an insect and a mammalian host and is the causative agent of sleeping sickness. Here, we performed the first genome-wide mapping of 2'-O-methylation (Nm) on rRNA using two high-throughput sequencing methods, RibOxi-seq and 2'-O-Me-seq. The sequencing revealed 97 Nms guided by 85 snoRNAs. At least twenty-six sites were found to be hypermodified in the bloodstream form of the parasites that propagates in the mammalian host compared to the procyclic stage that infects the fly. We demonstrate that predicted Nm based on bioinformatics do not always exist, suggesting that despite obeying the guiding rules there must be other factors that determine whether a snoRNA guides a specific modification. Silencing of the snoRNA that guides three hypermodified positions affected rRNA biogenesis and the ability of the parasite to cope with growth at elevated temperatures. This is the first system demonstrating that changes in a single modification guided by C/D snoRNA has direct consequences on cell growth.