(5'S)-8,5'-cyclo-2'-deoxyguanosine is a Strong Block to Replication, a Potent Pol V-dependent Mutagenic Lesion, and is Inefficiently Repaired in Escherichia Coli
Overview
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8,5'-Cyclopurines, making up an important class of ionizing radiation-induced tandem DNA damage, are repaired only by nucleotide excision repair (NER). They accumulate in NER-impaired cells, as in Cockayne syndrome group B and certain Xeroderma Pigmentosum patients. A plasmid containing (5'S)-8,5'-cyclo-2'-deoxyguanosine (S-cdG) was replicated in Escherichia coli with specific DNA polymerase knockouts. Viability was <1% in the wild-type strain, which increased to 5.5% with SOS. Viability decreased further in a pol II(-) strain, whereas it increased considerably in a pol IV(-) strain. Remarkably, no progeny was recovered from a pol V(-) strain, indicating that pol V is absolutely required for bypassing S-cdG. Progeny analyses indicated that S-cdG is significantly mutagenic, inducing ~34% mutation with SOS. Most mutations were S-cdG → A mutations, though S-cdG → T mutation and deletion of 5'C also occurred. Incisions of purified UvrABC nuclease on S-cdG, S-cdA, and C8-dG-AP on a duplex 51-mer showed that the incision rates are C8-dG-AP > S-cdA > S-cdG. In summary, S-cdG is a major block to DNA replication, highly mutagenic, and repaired slowly in E. coli.
Karwowski B Antioxidants (Basel). 2023; 12(4).
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Boguszewska K, Kazmierczak-Baranska J, Karwowski B Molecules. 2021; 26(22).
PMID: 34834133 PMC: 8623968. DOI: 10.3390/molecules26227042.
Kant M, Jaruga P, Coskun E, Ward S, Stark A, Baumann T ACS Omega. 2021; 6(25):16600-16611.
PMID: 34235332 PMC: 8246699. DOI: 10.1021/acsomega.1c01954.
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Szewczuk M, Boguszewska K, Kazmierczak-Baranska J, Karwowski B Molecules. 2021; 26(12).
PMID: 34205449 PMC: 8234751. DOI: 10.3390/molecules26123750.
Boguszewska K, Szewczuk M, Kazmierczak-Baranska J, Karwowski B Cells. 2021; 10(4).
PMID: 33805115 PMC: 8064110. DOI: 10.3390/cells10040725.