TY  - INPR
A1  - Neitz, Hermann
A1  - Bessi, Irene
A1  - Kuper, Jochen
A1  - Kisker, Caroline
A1  - Höbartner, Claudia
T1  - Programmable DNA interstrand crosslinking by alkene-alkyne [2+2] photocycloaddition
T2  - Journal of the American Chemical Society
N2  - Covalent crosslinking of DNA strands provides a useful tool for medical, biochemical and DNA nanotechnology applications. Here we present a light-induced interstrand DNA crosslinking reaction using the modified nucleoside 5-phenylethynyl-2’-deoxyuridine (\(^{Phe}\)dU). The crosslinking ability of \(^{Phe}\)dU was programmed by base pairing and by metal ion interaction at the Watson-Crick base pairing site. Rotation to intrahelical positions was favored by hydrophobic stacking and enabled an unexpected photochemical alkene-alkyne [2+2] cycloaddition within the DNA duplex, resulting in efficient formation of a \(^{Phe}\)dU-dimer after short irradiation times of a few seconds. A \(^{Phe}\)dU dimer-containing DNA was shown to efficiently bind a helicase complex, but the covalent crosslink completely prevented DNA unwinding, suggesting possible applications in biochemistry or structural biology.
KW  - light-induced interstrand DNA crosslinking
KW  - alkene-alkyne [2+2] photocycloaddition
KW  - DNA-based nanostructures
KW  - DNA-processing enzymes
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-311822
N1  - This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Journal of the American Chemical Society, copyright © 2023 The Authors. Published by American Chemical Society. after peer review. To access the final edited and published work see https://doi.org/10.1021/jacs.3c01611.
ET  - submitted version
ER  - 
TY  - INPR
A1  - Scheitl, Carolin P. M.
A1  - Mieczkowski, Mateusz
A1  - Schindelin, Hermann
A1  - Höbartner, Claudia
T1  - Structure and mechanism of the methyltransferase ribozyme MTR1
T2  - Nature Chemical Biology
N2  - RNA-catalysed RNA methylation was recently shown to be part of the catalytic repertoire of ribozymes. The methyltransferase ribozyme MTR1 catalyses the site-specific synthesis of 1-methyladenosine (m\(^1\)A) in RNA, using O\(^6\)-methylguanine (m\(^6\)G) as methyl group donor. Here we report the crystal structure of MTR1 at a resolution of 2.8 Å, which reveals a guanine binding site reminiscent of natural guanine riboswitches. The structure represents the postcatalytic state of a split ribozyme in complex with the m1A-containing RNA product and the demethylated cofactor guanine. The structural data suggest the mechanistic involvement of a protonated cytidine in the methyl transfer reaction. A synergistic effect of two 2'-O-methylated ribose residues in the active site results in accelerated methyl group transfer. Supported by these results, it seems plausible that modified nucleotides may have enhanced early RNA catalysis and that metabolite-binding riboswitches may resemble inactivated ribozymes that have lost their catalytic activity during evolution.
KW  - Methyltransferase Ribozyme MTR1
KW  - Crystal structure of MTR1
KW  - RNA-catalyzed RNA methylation
KW  - X-ray crystallography
KW  - RNA
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-272170
ET  - submitted version
ER  -