Adenine N3 position in the DNA minor groove (N3-adenine) (N3-adenine)

The N3 position of adenine is a critical nucleophilic site located within the minor groove of the DNA double helix [1]. It is a primary target for various DNA-damaging agents, particularly alkylating chemotherapeutics like temozolomide and CC-1065, which form 3-alkyladenine adducts [2]. These adducts are highly cytotoxic because they physically obstruct the progression of DNA and RNA polymerases, leading to replication arrest and apoptosis [3]. In addition to covalent modification, the N3 atom serves as an important hydrogen bond acceptor for non-covalent minor groove binding ligands, such as netropsin and distamycin, which are used to target specific DNA sequences [4]. While targeting this site is effective in treating various cancers, it also poses risks of mutagenicity and secondary cancers due to the potential for miscoding or incomplete repair by the base excision repair pathway [5]. The repair of N3-adenine lesions is primarily mediated by the enzyme alkyladenine DNA glycosylase (AAG), also known as N-methylpurine DNA glycosylase (MPG) [6].

Other names

N3-adenine3-adenyl siteMinor groove adenine N33-methyladenine siteN3-MeA site

Covalent alkylation of the N3 nitrogen of adenine in the DNA minor groove, leading to replication fork stalling and apoptosis, or non-covalent binding to the minor groove to displace transcription factors.