TY - JOUR
T1 - DNA sequence context greatly affects the accuracy of bypass across an ultraviolet light 6-4 photoproduct in mammalian cells
AU - Shriber, Pola
AU - Leitner-Dagan, Yael
AU - Geacintov, Nicholas
AU - Paz-Elizur, Tamar
AU - Livneh, Zvi
N1 - Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/10/1
Y1 - 2015/10/1
N2 - Translesion DNA synthesis (TLS) is a DNA damage tolerance mechanism carried out by low-fidelity DNA polymerases that bypass DNA lesions, which overcomes replication stalling. Despite the miscoding nature of most common DNA lesions, several of them are bypassed in mammalian cells in a relatively accurate manner, which plays a key role maintaining a low mutation load. Whereas it is generally agreed that TLS across the major UV and sunlight induced DNA lesion, the cyclobutane pyrimidine dimer (CPD), is accurate, there were conflicting reports on whether the same is true for the thymine-thymine pyrimidine-pyrimidone(6-4) ultraviolet light photoproduct (TT6-4PP), which represents the second most common class of UV lesions. Using a TLS assay system based on gapped plasmids carrying site-specific TT6-4PP lesions in defined sequence contexts we show that the DNA sequence context markedly affected both the extent and accuracy of TLS. The sequence exhibiting higher TLS exhibited also higher error-frequency, caused primarily by semi-targeted mutations, at the nearest nucleotides flanking the lesion. Our results resolve the discrepancy reported on TLS across TT6-4PP, and suggest that TLS is more accurate in human cells than in mouse cells.
AB - Translesion DNA synthesis (TLS) is a DNA damage tolerance mechanism carried out by low-fidelity DNA polymerases that bypass DNA lesions, which overcomes replication stalling. Despite the miscoding nature of most common DNA lesions, several of them are bypassed in mammalian cells in a relatively accurate manner, which plays a key role maintaining a low mutation load. Whereas it is generally agreed that TLS across the major UV and sunlight induced DNA lesion, the cyclobutane pyrimidine dimer (CPD), is accurate, there were conflicting reports on whether the same is true for the thymine-thymine pyrimidine-pyrimidone(6-4) ultraviolet light photoproduct (TT6-4PP), which represents the second most common class of UV lesions. Using a TLS assay system based on gapped plasmids carrying site-specific TT6-4PP lesions in defined sequence contexts we show that the DNA sequence context markedly affected both the extent and accuracy of TLS. The sequence exhibiting higher TLS exhibited also higher error-frequency, caused primarily by semi-targeted mutations, at the nearest nucleotides flanking the lesion. Our results resolve the discrepancy reported on TLS across TT6-4PP, and suggest that TLS is more accurate in human cells than in mouse cells.
KW - DNA damage
KW - DNA repair
KW - Error-prone repair
KW - Lesion bypass
KW - UV mutagenesis
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U2 - 10.1016/j.mrfmmm.2015.08.002
DO - 10.1016/j.mrfmmm.2015.08.002
M3 - Article
C2 - 26302378
AN - SCOPUS:84940044140
SN - 0027-5107
VL - 780
SP - 71
EP - 76
JO - Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
JF - Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis
ER -