Functional Characterization of Cytosine DNA Methyltransferase 2 DNMT2 in Plants

Abstract

DNA methyltransferase 2(DNMT2) is a cytosine methyltransferase that belongs to DNA newlinemethyltransferase family. Structurally, DNMT2 resembles other members of the newlinemethyltransferase family and possesses the characteristic catalytic motifs at the C-terminal end. newlineHowever, unlike the other members it lacks the regulatory domains at the N-terminal end. Most newlineimportantly, using the catalytic mechanism of a typical DNA methyltransferase DNMT2 newlinerobustly catalyzes the transfer of methyl group from S-adenosyl-L-methionine to the 5th carbon newlineof cytosines located in RNAs rather than DNA. Cytosine located at position 38 in the anticodon newlineloop of tRNAAspis known to be the universal substrate of DNMT2 across plant and animal newlinesystems (Goll et al. 2006). In some organisms it is known to target C38 in tRNAGlu, tRNAGly newline, newlinetRNAVal and cytosines in tRNA-like folded regions in mRNAs. Hence, DNMT2 has been aptly newlinereferred to as RNA methyltransferase and has been renamed Transfer RNA Aspartic Acid newlineMethyltransferase 1 (TRDMT1/DNMT2). TRDMT1/DNMT2-mediated cytosine methylation in newlinespecific tRNAs has been correlated with regulation of protein translation. Specifically, activity newlineof TRDMT1/DNMT2 affects efficiency and accuracy of decoding, increases amino acid newlineaccepting capacity of specific tRNAs and affects synthesis of poly-Asp proteins. newlineTRDMT1/DNMT2-mediated C38 methylation has also been correlated with tRNA stability and newlineprotection of tRNAs from ribonuclease cleavage under stress. Unlike the extensive studies newlinereported on biological functions of TRDMT1/DNMT2 in animal model systems, limited newlineinformation on its cellular functions is available in land plants. Our lab had previously reported newlinethat loss of TRDMT1/DNMT2 in the moss Physcomitrium leads to increased sensitivity of newlineplants to oxidative and osmotic stress. This has been correlated with reduced stability of newlinetRNAAspunder stress and to mis-regulation of a number of genes involved in stress perception newlineand signaling (Arya et al., 2016; Singh et al., 2020). With the aim of gaining deeper...