RNAs are post-transcriptionally modified in all kingdoms of life. Of these modifications, base methylations are highly conserved in eukaryote ribosomal RNA (rRNA). Recently, rRNA processing protein 8 (Rrp8) and nucleomethylin (NML) were identified as factors of N1-methyladenosine (
m1A) modification in yeast 25S and mammalian 28S rRNA, respectively. However,
m1A modification of rRNA is still poorly understood in Caenorhabditis elegans. Here, using the liquid chromatography/tandem mass spectrometry analysis and RNA immunoprecipitation (RIP) assay, we have identified that
m1A modification is located around position 674 (A674) of 26S rRNA in C. elegans. Furthermore, quantitative PCR-based analysis revealed that T07A9.8, a C. elegans homolog of yeast Rrp8 and human NML, is responsible for
m1A modification at A674 of 26S rRNA. This
m1A modification site in C. elegans corresponds to those in yeast 25S rRNA and human 28S rRNA. Intriguingly, T07A9.8 is not associated with pre-rRNA transcription under normal nutrient conditions. Since
m1A modification of 26S rRNA requires T07A9.8 in C. elegans, we designated the gene as rRNA adenine methyltransferase-1 (
rram-1).