2021

Acta Crystallographica Section B-Structural Science Crystal Engineering and Materials

Rocznik: 2021 | Tom: 77 | Numer: 3

artykuł naukowy

angielski

EN The X-ray crystal structure of the d(CGCGCG)(2)/putrescine(2(+))/K+ complex has been determined at 0.60 angstrom resolution. Stereochemical restraints were used only for the putrescinium dication, and 23 bonds and 18 angles of the Z-DNA nucleotides with dual conformation. The N atoms of the putrescine(2(+)) dication form three direct hydrogen bonds with the N7_G atoms of three different Z-DNA molecules, plus three water-mediated hydrogen bonds with cytosine, guanine and phosphate acceptors. A unique potassium cation was also unambiguously identified in the structure, albeit at a similar to 0.5 occupation site shared with a water molecule, providing the first example of such a complex with Z-DNA. The K+ cation has coordination number of eight and an irregular coordination sphere, formed by four water molecules and four O atoms from two phosphate groups of the Z-DNA, including ligands present at fractional occupancy. The structural disorder of the Z-DNA duplex is manifested by the presence of alternate conformations along the DNA backbone. Comparison of the position and interactions of putrescine(2+) in the present structure with other ultra-high-resolution structures of Z-DNA in complexes with Mn2+ and Zn2+ ions shows that the dicationic putrescinium moiety can effectively substitute these metal ions for stabilization of Z-type DNA duplexes. Furthermore, this comparison also suggests that the spermine(4+) tetracation has a higher affinity for Z-DNA than K+.

331 - 338

10.1107/S2052520621002663

http://journals.iucr.org/b/issues/2021/03/00/aw5052/aw5052.pdf

CC BY (uznanie autorstwa)

ostateczna wersja opublikowana

06.2021

w momencie opublikowania

140

140