A fungal dioxygenase CcTet serves as a eukaryotic 6mA demethylase on duplex DNA

Adenine methylation is very scarce in the drosophila genome and not erased by the Ten Eleven Translocation dioxygenase

“…Of note, only traces of 5mC, 5hmC, 5fC or 6mA were observed when recombinant TET was incubated with non-modified dsDNA, indicating that the levels measured in the presence of modified dsDNA were not due to contaminations (Supplementary Figure S5). Besides, it is worth mentioning that a distant TET homolog in the fungus Coprinosis cinerea was recently shown to oxidize both 5mC and 6mA (Mu et al ., 2022). Yet, its peculiar capacity to bind and demethylate 6mA requires key residues within its catalytic domain which are not conserved in other TET homologs including in drosophila (Supplementary Figure S6).…”

Drosophila TET acts with PRC1 to activate gene expression independently of its catalytic activity

“…In contrast with previous reports ( 33 , 37 ), our recent results indicate that TET does not act as a 6mA demethylase ( 41 ). Along that line, the capacity of a distant fungal TET homolog to target 6mA requires specific amino acids, which are not conserved among metazoan TETs ( 40 ). It is thus doubtful that TET catalytic function in the larval CNS is mediated by 6mA demethylation.…”

“…However, the direct impact of TET enzymes on mRNA modifications remains disputed notably because hm5C is essentially detected on tRNAs ( 23 , 24 , 37 ). In addition, the presence and potential significance of 6mA in metazoan genomes remain highly controversial ( 38 ), and the capacity of Drosophila TET to oxidize 6mA is at odds with the conserved structure of its catalytic domain (CD), which lacks crucial amino acids necessary for 6mA recognition and oxidation in more distant TET homologs or the related alkane hydroxylase AlkB family of 6mA demethylase ( 39 , 40 ). Along that line, our recent results support the conclusion that TET does not act as a 6mA demethylase in Drosophila and showed that, in contrast to TET expression, its catalytic activity is dispensable for adult fly emergence, survival, and reproduction ( 41 ).…”

Identification and Mechanism of Action of the Global Secondary Metabolism Regulator SaraC in Stereum hirsutum

“…There are still so many mysteries, such as how it works and how it impacts transcription that still have no clear conclusions. Ten-eleven translocation (TET) dioxygenase is the only known DNA demethylases that works on dsDNA ( 46 ), and one of its homolog enzyme CMD1 from the fungus Coprinopsis cinerea shows high abundances in 6mA modification by oxidizing 6mA to the intermediate N6-hydroxymethyladenosine ( 47 ). Our results show that SaraC functions in both 6mA and 5mC modifications, which removes the methyl directly based on the in vitro enzyme activity ( Fig.…”