(R1596) 1,N6-Ethenoadenosine, a Damaged Ribonucleotide in DNA: Impact on Translesion Synthesis and Repair

Pratibha Ghodke (Vanderbilt University School of Medicine)| Frederick Guengerich (Vanderbilt University School of Medicine)

Ribonucleotides in DNA are poorly understood as instigators of DNA damage. In DNA, they can promote genomic instability by causing mutations and are also linked to several diseases. We investigated the impact of ribonucleotide rATP and its damaged analog 1,N6-ethenoadenosine (1,N6-εrA) on hpol η-mediated translesion synthesis (TLS) and RNase H2-mediated repair. Mass spectral analysis showed that 1,N6-εrA in DNA generates extensive frameshifts during TLS, which can lead to genomic instability. In addition to this, insertion of deoxypurines (dATP and dGTP) was dominantly seen opposite 1,N6-εrA in steady-state kinetic analysis for the TLS process. The repair studies revealed that RNase H2 recognizes but exhibits partial incision activity across from 1,N6-εrA in DNA, which can lead to the persistence of this adduct into DNA. Our findings identify the mutagenic potential of an unrepaired damaged ribonucleotide 1,N6-εrA in DNA, which can change the reading frame of mRNA.