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Human AlkB Homolog ABH8 Is a tRNA Methyltransferase Required for Wobble Uridine Modification and DNA Damage Survival

2010; Taylor & Francis; Volume: 30; Issue: 10 Linguagem: Inglês

10.1128/mcb.01604-09

1098-5549

Dragony Fu, Jennifer A. N. Brophy, Clement T. Y. Chan, Kyle Aaquil Atmore, Ulrike Begley, Richard S. Paules, Peter C. Dedon, Thomas J. Begley, Leona D. Samson,

Epigenetics and DNA Methylation

AbstracttRNA nucleosides are extensively modified to ensure their proper function in translation. However, many of the enzymes responsible for tRNA modifications in mammals await identification. Here, we show that human AlkB homolog 8 (ABH8) catalyzes tRNA methylation to generate 5-methylcarboxymethyl uridine (mcm5U) at the wobble position of certain tRNAs, a critical anticodon loop modification linked to DNA damage survival. We find that ABH8 interacts specifically with tRNAs containing mcm5U and that purified ABH8 complexes methylate RNA in vitro. Significantly, ABH8 depletion in human cells reduces endogenous levels of mcm5U in RNA and increases cellular sensitivity to DNA-damaging agents. Moreover, DNA-damaging agents induce ABH8 expression in an ATM-dependent manner. These results expand the role of mammalian AlkB proteins beyond that of direct DNA repair and support a regulatory mechanism in the DNA damage response pathway involving modulation of tRNA modification. We thank Peter Svensson and Emma Wang for the URM1 knockdown cell line and the Klungland and Falnes labs for sharing unpublished results.This work was supported by NIH grants CA055042 and ES002109 to L.D.S. and ES01701 to T.J.B., by the Intramural Research Program of the NIH (R.S.P.), and by the MIT Westaway Fund and NCRR grant S10-RR023783 to P.C.D. D.F. is supported by an American Cancer Society TJX Postdoctoral Fellowship, and L.D.S. is an American Cancer Society Research Professor.