7atg

Publication Abstract from PubMed

The X-ray crystal structure of the d(CGCGCG)2/putrescine(2+)/K(+) complex has been determined at 0.60 A 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 approximately 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 Mn(2+) and Zn(2+) 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(+).

Crystal structure of Z-DNA in complex with the polyamine putrescine and potassium cations at ultra-high resolution.,Drozdzal P, Gilski M, Jaskolski M Acta Crystallogr B Struct Sci Cryst Eng Mater. 2021 Jun 1;77(Pt 3):331-338. doi: , 10.1107/S2052520621002663. Epub 2021 May 6. PMID:34096514^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.