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.
Departament d'Enginyeria Quimica, ETSEIB-UPC, Barcelona, Spain.
Hans
H
Millonig
Joan
J
Pous
Catherine
C
Gouyette
Juan A
JA
Subirana
J Lourdes
JL
Campos
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