TY - JOUR
T1 - Electron trap for DNA-bound repair enzymes
T2 - A strategy for DNA-mediated signaling
AU - Yavin, Eylon
AU - Stemp, Eric D.A.
AU - O'Shea, Valerie L.
AU - David, Sheila S.
AU - Barton, Jacqueline K.
PY - 2006/3/7
Y1 - 2006/3/7
N2 - Despite a low copy number within the cell, base excision repair (BER) enzymes readily detect DNA base lesions and mismatches. These enzymes also contain [Fe4S4] clusters, yet a redox role for these iron cofactors had been unclear. Here, we provide evidence that BER proteins may use DNA-mediated redox chemistry as part of a signaling mechanism to detect base lesions. By using chemically modified bases, we show electron trapping on DNA in solution with bound BER enzymes by electron paramagnetic resonance (EPR) spectroscopy. We demonstrate electron transfer from two BER proteins, Endonuclease III (EndoIII) and MutY, to modified bases in DNA containing oxidized nitroxyl radical EPR probes. Electron trapping requires that the modified base is coupled to the DNA π-stack, and trapping efficiency is increased when a non-cleavable MutY substrate analogue is located distally to the trap. These results are consistent with DNA binding leading to the activation of the repair proteins toward oxidation. Significantly, these results support a mechanism for DNA repair that involves DNA-mediated charge transport.
AB - Despite a low copy number within the cell, base excision repair (BER) enzymes readily detect DNA base lesions and mismatches. These enzymes also contain [Fe4S4] clusters, yet a redox role for these iron cofactors had been unclear. Here, we provide evidence that BER proteins may use DNA-mediated redox chemistry as part of a signaling mechanism to detect base lesions. By using chemically modified bases, we show electron trapping on DNA in solution with bound BER enzymes by electron paramagnetic resonance (EPR) spectroscopy. We demonstrate electron transfer from two BER proteins, Endonuclease III (EndoIII) and MutY, to modified bases in DNA containing oxidized nitroxyl radical EPR probes. Electron trapping requires that the modified base is coupled to the DNA π-stack, and trapping efficiency is increased when a non-cleavable MutY substrate analogue is located distally to the trap. These results are consistent with DNA binding leading to the activation of the repair proteins toward oxidation. Significantly, these results support a mechanism for DNA repair that involves DNA-mediated charge transport.
KW - Base excision repair
KW - DNA charge transport
KW - Iron sulfur clusters
UR - http://www.scopus.com/inward/record.url?scp=33644857131&partnerID=8YFLogxK
U2 - 10.1073/pnas.0600239103
DO - 10.1073/pnas.0600239103
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
C2 - 16505354
AN - SCOPUS:33644857131
SN - 0027-8424
VL - 103
SP - 3610
EP - 3614
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 10
ER -