Somatic cancer mutations in the DNMT2 tRNA methyltransferase alter its catalytic properties.
Methylation of tRNA is an important post-transcriptional modification and aberrations in tRNA modification has been implicated in cancer. The DNMT2 protein methylates C38 of tRNA-Asp and it has a role in cellular physiology and stress response and its expression levels are altered in cancer tissues. Here we studied whether DNMT2 somatic mutations found in cancer tissues affect the activity of the enzyme. We have generated 13 DNMT2 variants and purified the corresponding proteins. All proteins were properly folded as determined by circular dichroism spectroscopy. We tested their RNA methylation activity using in vitro generated tRNA-Asp. One of the mutations (E63K) caused a twofold increase in activity, while two of them led to a strong (over fourfold) decrease in activity (G155S and L257V). Two additional mutant proteins were almost inactive (R371H and G155V). The strong effect of some of the somatic cancer mutations on DNMT2 activity suggests that these mutations have a functional role in tumorigenesis.
Institute of Biochemistry, Stuttgart University, 70569 Stuttgart, Germany.
Winfried
W
Elhardt
Institute of Biochemistry, Stuttgart University, 70569 Stuttgart, Germany.
Raghuvaran
R
Shanmugam
Institute of Biochemistry, Stuttgart University, 70569 Stuttgart, Germany. Electronic address: tomasz.jurkowski@ibc.uni-stuttgart.de.
Tomasz P
TP
Jurkowski
Institute of Biochemistry, Stuttgart University, 70569 Stuttgart, Germany. Electronic address: albert.jeltsch@ibc.uni-stuttgart.de.
Albert
A
Jeltsch
D019943:Amino Acid Substitution; D000818:Animals; D002384:Catalysis; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008745:Methylation; D051379:Mice; D020125:Mutation, Missense; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009369:Neoplasms / Q000201:enzymology* / Q000235:genetics; D012323:RNA Processing, Post-Transcriptional; D012349:RNA, Transfer, Asp / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D009363:Neoplasm Proteins; D012349:RNA, Transfer, Asp; D004248:DNA (Cytosine-5-)-Methyltransferases; C112218:TRDMT1 protein, human
Cancer; Dnmt2; Somatic mutation; tRNA methylation