Mouse Tet1 protein can oxidize 5mC to 5hmC and 5caC on Single-stranded DNA

Abstract

5-Methylcytosine (5 mC) is known to play broad roles in mammalian biology. It can be enzymatically oxidized to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5 fC), and 5-carboxylcytosine (5 caC) by a family of iron (II)/αKG-dependent dioxygenases Tet proteins. This process has been shown to play critical roles in mammalian cell development and dynamic methylation regulation. Previous research has shown that Tet proteins can oxidize 5mC on double-stranded DNA (dsDNA). Here, we expressed and purified the active domain of mouse Tet1 DNA from insect cell. By employing mass spectrometry, we show here that mtet1 (1367-2039) can also oxidize 5 mC on single-stranded DNA (ssDNA), thus indicating its potential involvement in 5 mC oxidation during replication or/and transcription, as well as the oxidation of corresponding modifications on single-stranded RNA in mammalian cells. © 2012 Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.