title: Improved synthesis and mutagenicity of oligonucleotides containing 5-hydroxymethylcytosine, 5-formylcytosine and 5-carboxylcytosine.
abstract: 5-Formylcytosine (fC or (5-CHO)dC) and 5-carboxylcytosine (caC or (5-COOH)dC) have recently been identified as constituents of mammalian DNA. The nucleosides are formed from 5-methylcytosine (mC or (5-Me)dC) via 5-hydroxymethylcytosine (hmC or (5-HOMe)dC) and are possible intermediates of an active DNA demethylation process. Here we show efficient syntheses of phosphoramidites which enable the synthesis of DNA strands containing these cytosine modifications based on Pd(0)-catalyzed functionalization of 5-iododeoxycytidine. The first crystal structure of fC reveals the existence of an intramolecular H-bond between the exocyclic amine and the formyl group, which controls the conformation of the formyl substituent. Using a newly designed in vitro mutagenicity assay we show that fC and caC are only marginally mutagenic, which is a prerequisite for the bases to function as epigenetic control units.
authors: Center for Integrated Protein Science (CiPSM) at the Department of Chemistry, Ludwig-Maximilians-University, Butenandtstr. 5-13, 81377 Munich, Germany.
authors: Martin
authors: M
authors: Münzel
authors: Ulrike
authors: U
authors: Lischke
authors: Dimitrios
authors: D
authors: Stathis
authors: Toni
authors: T
authors: Pfaffeneder
authors: Felix A
authors: FA
authors: Gnerlich
authors: Christian A
authors: CA
authors: Deiml
authors: Sandra C
authors: SC
authors: Koch
authors: Konstantin
authors: K
authors: Karaghiosoff
authors: Thomas
authors: T
authors: Carell
mesh_terms: D044503:5-Methylcytosine / Q000031:analogs & derivatives; D002851:Chromatography, High Pressure Liquid; D003596:Cytosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D019175:DNA Methylation; D015394:Molecular Structure; D009153:Mutagens / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D009841:Oligonucleotides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D009943:Organophosphorus Compounds / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D009153:Mutagens; D009841:Oligonucleotides; D009943:Organophosphorus Compounds; C434331:phosphoramidite; C011865:5-hydroxymethylcytosine; D044503:5-Methylcytosine; D003596:Cytosine