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Improved Synthesis and Mutagenicity of Oligonucleotides Containing 5‐Hydroxymethylcytosine, 5‐Formylcytosine and 5‐Carboxylcytosine
Author(s) -
Münzel Martin,
Lischke Ulrike,
Stathis Dimitrios,
Pfaffeneder Toni,
Gnerlich Felix A.,
Deiml Christian A.,
Koch Sandra C.,
Karaghiosoff Konstantin,
Carell Thomas
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201102782
Subject(s) - 5 hydroxymethylcytosine , dna demethylation , chemistry , dna , demethylation , oligonucleotide , epigenetics , cytosine , substituent , stereochemistry , combinatorial chemistry , intramolecular force , amine gas treating , dna methylation , biochemistry , organic chemistry , gene , gene expression
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.