Crystal structure of Z-DNA in complex with the polyamine putrescine and potassium cations at ultra-high resolution.

ABSTRACT: The X-ray crystal structure of the d(CGCGCG)₂/putrescine(2+)/K⁺ complex has been determined at 0.60 Å 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 ∼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,

SUBMITTER: Drozdzal P 

PROVIDER: S-EPMC8182800 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature