Cockayne syndrome: varied requirement of transcription-coupled nucleotide excision repair for the removal of three structurally different adducts from transcribed DNA.
Hereditary defects in the transcription-coupled nucleotide excision repair (TC-NER) pathway of damaged DNA cause severe neurodegenerative disease Cockayne syndrome (CS), however the origin and chemical nature of the underlying DNA damage had remained unknown. To find out, to which degree the structural properties of DNA lesions determine the extent of transcription arrest in human CS cells, we performed quantitative host cell reactivation analyses of expression vectors containing various synthetic adducts. We found that a single 3-(deoxyguanosin-N2-yl)-2-acetylaminofluorene adduct (dG(N2)-AAF) constitutes an unsurmountable obstacle to transcription in both CS-A and CS-B cells and is removed exclusively by the CSA- and CSB-dependent pathway. In contrast, contribution of the CS proteins to the removal of two other transcription-blocking DNA lesions - N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (dG(C8)-AAF) and cyclobutane thymine-thymine (TT) dimer - is only minor (TT dimer) or none (dG(C8)-AAF). The unique properties of dG(N2)-AAF identify this adduct as a prototype for a new class of DNA lesions that escape the alternative global genome repair and could be critical for the CS pathogenesis.
Institute of Pharmacy and Biochemistry, Johannes Gutenberg University of Mainz, Mainz, Germany.
Nataliya
N
Kitsera
Department of Chemistry and Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany.
Karola
K
Gasteiger
Institute of Pharmacy and Biochemistry, Johannes Gutenberg University of Mainz, Mainz, Germany.
Bork
B
Lühnsdorf
Institute of Pharmacy and Biochemistry, Johannes Gutenberg University of Mainz, Mainz, Germany.
Julia
J
Allgayer
Institute of Pharmacy and Biochemistry, Johannes Gutenberg University of Mainz, Mainz, Germany.
Bernd
B
Epe
Department of Chemistry and Biochemistry, Ludwig-Maximilians University Munich, Munich, Germany.
Thomas
T
Carell
Institute of Pharmacy and Biochemistry, Johannes Gutenberg University of Mainz, Mainz, Germany.
Andriy
A
Khobta
D002460:Cell Line; D003057:Cockayne Syndrome / Q000235:genetics*; D018736:DNA Adducts; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000494:pharmacology; D005449:Fluorenes / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D017930:Genes, Reporter; D006801:Humans; D000075223:Poly-ADP-Ribose Binding Proteins; D014158:Transcription, Genetic
C512721:3-(deoxyguanosin-N2-yl)-2-acetylaminofluorene; D018736:DNA Adducts; D005449:Fluorenes; D000075223:Poly-ADP-Ribose Binding Proteins; D004265:DNA Helicases; C078673:ERCC6 protein, human; D045643:DNA Repair Enzymes; D003849:Deoxyguanosine