1edr
From Proteopedia
MOLECULAR AND CRYSTAL STRUCTURE OF D(CGCGMO6AATTCGCG) AT 1.6 ANGSTROM
Overview
In a previous paper, 2'-deoxy-N(6)-methoxyadenosine (mo(6)A) was shown to form a mismatch base-pair with 2'-deoxycytidine with a Watson-Crick-type geometry. To fully understand the structural basis of genetic mutations with damaged DNA, it is necessary to examine whether the methoxylated adenine residue still has the ability to form the regular Watson-Crick pairing with a thymine residue. Therefore, a DNA dodecamer with the sequence d(CGCGmo(6)AATTCGCG) has been synthesized and its crystal structure determined. The methoxylation has no significant effect on the overall DNA conformation, which is that of a standard B-form duplex. The methoxylated adenine moieties adopt the amino tautomer with an anti conformation around the C(6)-N(6) bond to the N(1) atom, and they form a Watson-Crick base-pair with thymine residues on the opposite strand, similar to an unmodified adenine residue. It is concluded that methoxylated adenine can present two alternate faces for base-pairing, thanks to the amino<-->imino tautomerism allowed by methoxylation. Based on this property, two gene transition routes are proposed.
About this Structure
Full crystallographic information is available from OCA.
Reference
Crystallographic studies on damaged DNAs. II. N(6)-methoxyadenine can present two alternate faces for Watson-Crick base-pairing, leading to pyrimidine transition mutagenesis., Chatake T, Hikima T, Ono A, Ueno Y, Matsuda A, Takenaka A, J Mol Biol. 1999 Dec 17;294(5):1223-30. PMID:10600380 Page seeded by OCA on Fri May 2 14:58:24 2008
