Epigenetic effects of cytosine derivatives are caused by their tautomers in Hoogsteen base pairs

TL;DR

This paper investigates how the tautomeric forms of cytosine derivatives, particularly the imino tautomer, can form Hoogsteen base pairs with guanine, potentially explaining epigenetic effects observed in methylated cytosines.

Contribution

It proposes that the epigenetic effects of cytosine derivatives are caused by their ability to form Hoogsteen base pairs via the imino tautomer, detected using 1H15N NMR.

Findings

Imino tautomer of cytosine derivatives can form Hoogsteen GC base pairs.

Formation of Hoogsteen pairs may explain epigenetic effects of methylated cytosines.

Detection method suggested: 1H15N NMR.

Abstract

Deoxycitidine in solution exists as two tautomers one of which is an uncanonical imino one. The latter can dominate with such derivatives as 5-methyl, 5-hydroxymethyl- and 5-formylcytosine. The imino tautomer potentially is able to form a hoosteen GC base pair. To detect such pair, it is suggested to use 1H15N NMR. Formation of GC-Hoogsteen base pair with imino tautomer of cytosine can be a reason for epigenetic effects of 5-methyl- and 5-hydroxymethylcytosine.