J Biol Chem, Vol. 273, Issue 47, 30939-30944, November 20, 1998

Formation of a Complex Containing ATP, Mg²⁺, and Spermine
STRUCTURAL EVIDENCE AND BIOLOGICAL SIGNIFICANCE

Duangdeun Meksuriyen, Tomomi Fukuchi-Shimogori, Hideyuki Tomitori, Keiko Kashiwagi, Toshihiko Toida, Toshio Imanari, Gota Kawai^¶, and Kazuei Igarashi

From the  Faculty of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 and the ^¶ Department of Industrial Chemistry, Faculty of Engineering, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino-shi, Chiba 275-8588, Japan

The conformation of ATP in the presence of Mg²⁺ and/or spermine was studied by ³¹P and ¹H NMR, to clarify how polyamines interact with ATP. Spermine predominantly interacted with the - and -phosphates of ATP in the presence of Mg²⁺. A conformational change of the - and -phosphate of ATP with spermine could not be observed in the absence of Mg²⁺ by ³¹P NMR. It was found by ¹H NMR that the conformation of adenosine moiety of ATP was not influenced significantly by spermine. The binding of Mg²⁺ to ATP was slightly inhibited by spermine and vice versa. The results indicate that the binding sites of Mg²⁺ and spermine on ATP only partially overlap. The PotA protein, an ATP-dependent enzyme, was used as a model system to study the biological role of the ATP-Mg²⁺-spermine complex. The ATPase activity of PotA was greatly enhanced by spermine. Double reciprocal plots at several concentrations of spermine as an activator indicate that spermine interacts with ATP, but not with PotA. The activity of protein kinase A was also stimulated about 2-fold by spermine. The results suggest that a ternary complex of ATP-Mg²⁺-spermine may play an important role in some ATP-dependent reactions in vivo and in the physiological effects of endogenous polyamines.