snoRNA-guided tRNA 2'-O-methylation controls codon-biased gene expression and cellular states

snoRNAs are a large family of noncoding (nc)RNAs present across eukaryotes and archaea. While a subset of them guide 2-O- methylation (Nm) and pseudouridylation ({Psi}) of rRNAs and snRNAs, targets of most snoRNAs remain unknown. Here we used PARIS2 to map snoRNA targets, revealing an extensive and conserved snoRNA-tRNA interaction network. Using optimized denatured RiboMeth-seq (dRMS), we discovered snoRNA-guided Nm sites in ncRNAs, including tRNAs. Loss of snoRNAs and their associated 2-O-methyltransferase FBL reduced tRNA modifications and increased fragmentation. CRISPR knockout of the D97/D133 family of snoRNAs reduced the activity and levels of several target tRNAs, including elongator (e)Met-CAU, leading to codon-biased transcriptome and translatome in human cells. The codon-biased gene expression tipped the balance between the dichotomous cellular states of proliferation and differentiation, and skewed germ layer potential of mouse embryonic stem cells. Together, we discovered a snoRNA-guided tRNA modification mechanism controlling codon-biased gene expression and cellular states.