The interaction of manganese ions with DNA.
We present the structure of the duplex formed by a fragment of auto-complementary DNA with the sequence d(CGTTAATTAACG). The structure was determined by X-ray crystallography. Up to date it is the first structure presenting the interaction between a DNA oligonucleotide and manganese ions. The presence of Mn2+ creates bonds among the N7 atom of guanines and phosphates. These bonds stabilize and determine the crystallographic network in a P3(2) space group, unusual in oligonucleotide crystals. The crystal structure observed is compared with those found in the presence of Mg2+, Ca2+ and Ni2+, which show different kinds of interactions. The double helices show end-to-end interactions, in a manner that the terminal guanines interact with the minor groove of the neighboring duplex, while the terminal cytosines are disordered. We have chosen this sequence since it contains a TTAA repeat. Such repeats are very rare in all genomes. We suggest that this sequence may be very susceptible to the formation of closely spaced thymine dimers.
Millonig
Hans
H
Departament d'Enginyeria Quimica, ETSEIB-UPC, Barcelona, Spain.
Pous
Joan
J
Gouyette
Catherine
C
Subirana
Juan A
JA
Campos
J Lourdes
JL
D001483:Base Sequence; D001665:Binding Sites; D002413:Cations, Divalent; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D012091:Repetitive Sequences, Nucleic Acid
D002413:Cations, Divalent; D008345:Manganese; D004247:DNA