Project description:DNA methylation is a key epigenetic modification regulating genome organization, stability, and gene expression. Stable DNA methylation critically relies on methyl groups provided through folate-mediated one-carbon (C1) metabolism, yet the origin and regulation of C1 supply remain elusive. Here we demonstrate that photorespiration serves as a major C1 source for DNA methylation in Arabidopsis. We show that C1 from formate, a photorespiratory byproduct, is incorporated into 5-methyl-cytosine via the reductive cytosolic folate pathway. This occurs predominantly during the day, negatively regulating serine utilization as alternative C1 source. Consequently, suppression of photorespiration under elevated CO₂ levels alters the DNA methylation landscape, an effect exacerbated when regulation of C1 metabolism by the formate-dependent pathway is impaired. Thus, our findings link the fundamental metabolic process of photorespiration to epigenetic stability, highlighting how rising atmospheric CO₂ levels can induce DNA methylation changes.
Project description:Leishmania cause cutaneous and visceral diseases affecting millions worldwide. The parasite cycle between insect and mammalian hosts. In this study, we determined the landscape of this 2’-O- methylation (Nm) modification on the rRNA and found that two positions change during cycling between its two life stages. Overexpression of LM32Cs1C1 snoRNA guiding one of these positions compromised growth affecting translation. CryoEM structure of ribosomes from cells overexpressing the snoRNA and its mutant version that cannot guide Nm at ~2.4 Å resolution, suggested no structural changes in small subunit rRNA carrying the Nm modification but changes were observed in H68 of the large subunit rRNA reflecting the function of a second rRNA interaction domain with the snoRNA.
Project description:In this study we profiled the complete repertoire of 2'-O-methylation sites present in the rRNA and a subset of small RNAs of Leishmania major rRNA using RibOxi-seq.