1 Department of Chemistry and Biochemistry, Concordia University Montreal, 7141 Sherbrooke Street W., Montreal, Quebec, H4B 1R6, Canada.
2 Present address: Howard Hughes Medical Institute, Department of Molecular Biology and, Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, MA, 02114, USA.

AGT Activity Towards Intrastrand Crosslinked DNA is Modulated by the Alkylene Linker.

Chembiochem. 2017 12 05;18(23):2351-2357

Authors: O'Flaherty DK, Wilds CJ

Abstract

DNA oligomers containing dimethylene and trimethylene intrastrand crosslinks (IaCLs) between the O4 and O6 atoms of neighboring thymidine (T) and 2'-deoxyguanosine (dG) residues were prepared by solid-phase synthesis. UV thermal denaturation (Tm ) experiments revealed that these IaCLs had a destabilizing effect on the DNA duplex relative to the control. Circular dichroism spectroscopy suggested these IaCLs induced minimal structural distortions. Susceptibility to dealkylation by reaction with various O6 -alkylguanine DNA alkyltransferases (AGTs) from human and Escherichia coli was evaluated. It was revealed that only human AGT displayed activity towards the IaCL DNA, with reduced efficiency as the IaCL shortened (from four to two methylene linkages). Changing the site of attachment of the ethylene linkage at the 5'-end of the IaCL to the N3 atom of T had minimal influence on duplex stability and structure, and was refractory to AGT activity.

PMID: 28980757 [PubMed - indexed for MEDLINE]