Direct interactions between Z-DNA and alkaline earth cations, discovered in the presence of high concentrations of MgCl2 and CaCl2

作者：Chatake Toshiyuki^*; Sunami Tomoko

来源：Journal of Inorganic Biochemistry, 2013, 124: 15-25.

DOI：10.1016/j.jinorgbio.2013.03.004

• Z-DNA
• Alkaline earth cations
• DNA assembly

In this study, crystals of Z-DNA hexamer d(CGCGCG) complexed with MgCl2 and CaCl2 were obtained in the presence of high concentrations of alkaline earth salts (500 mM) using a temperature control technique, and their crystal structures were determined at 1.3 angstrom resolution. Mg2+ and Ca2+ cations in these structures tend to interact directly with phosphate groups of Z-DNA duplexes: however, they tend to form water-mediated interactions with Z-DNA in the presence of lower concentrations of alkaline earth salts. In these crystals, a DNA duplex was laid along its c-axis and interacted with its 6 neighboring DNA duplexes through coordination bonds of P-O-center dot center dot center dot(Mg2+ or Ca2+)(center dot center dot center dot)O-P. A symmetrical hexagonal Z-DNA duplex assembly model may explain DNA condensation caused by alkaline earth salts. These structures offer insights into the functions of alkaline earth cations essential to the structures and assembly of Z-DNA duplexes.

• 出版日期2013-7