Abstract
Dimethyladenosine transferase 1 (DIMT1) is an evolutionarily conserved RNA N6,6-dimethyladenosine (m26,6A) methyltransferase. DIMT1 plays an important role in ribosome biogenesis, and the catalytic activity of DIMT1 is indispensable for cell viability and protein synthesis. A few RNA-modifying enzymes can install the same modification in multiple RNA species. However, whether DIMT1 can work on RNA species other than 18S rRNA is unclear. Here, we describe that DIMT1 generates m26,6A not only in 18S rRNA but also in small RNAs. In addition, m26,6A in small RNAs were significantly decreased in cells expressing catalytically inactive DIMT1 variants (E85A or NLPY variants) compared with cells expressing wildtype DIMT1. Both E85A and NLPY DIMT1 variant cells present decreased protein synthesis and cell viability. Furthermore, we observed that DIMT1 is highly expressed in human cancers, including acute myeloid leukemia. Our data suggest that downregulation of DIMT1 in acute myeloid leukemia cells leads to a decreased m26,6A level in small RNAs. Together, these data suggest that DIMT1 not only installs m26,6A in 18S rRNA but also generates m26,6A-containing small RNAs, both of which potentially contribute to the impact of DIMT1 on cell viability and gene expression.
Highlights
To obvious growth defects in comparison to the wildtype strain [3]
The results showed that two rounds of polydT extraction followed by one round of RiboMinus purification lead to inappreciable levels of 18S rRNA in the remaining RNA species, which is supported by the bioanalyzer results (Fig. S1C)
Since we observed that the E85A Dimethyladenosine transferase 1 (DIMT1) variant leads to a significant impact on m26,6A levels in 18S rRNA and protein synthesis [5], we studied the impact of NLPY DIMT1 variant on the level of m26,6A on 18S rRNA, 18S processing, 40S assembly, and global protein synthesis
Summary
The two adjacent m26,6A are located at the interface between the 40S ribosome small subunit and the 60S large subunit, contacting tRNA and mRNA during translation These two m26,6A sites in 18S rRNA are nearly fully methylated (96% occupancy) [1, 16]. RNA species, including small RNAs. There are multiple types of small RNAs such as 5S rRNA, snRNA, tRNAs, and microRNAs containing enzyme-mediated chemical modifications [26]. There are multiple types of small RNAs such as 5S rRNA, snRNA, tRNAs, and microRNAs containing enzyme-mediated chemical modifications [26] These modifications on small RNAs can dramatically influence the functions of small RNAs. For instance, in the major spliceosomal snRNAs, multiple pseudouridines and 20-O-methylated nucleotides have been detected [27]. We investigated whether DIMT1 generates m26,6A-containing RNA species other than 18S rRNA and the potential biological function from DIMT1mediated m26,6A on RNA species
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