Petrushanko Irina Yu, Mitkevich Vladimir A, Anashkina Anastasia A, Klimanova Elizaveta A, Dergousova Elena A, Lopina Olga D, Makarov Alexander A
1] Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov St. 32, 119991 Moscow, Russia [2].
Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov St. 32, 119991 Moscow, Russia.
Sci Rep. 2014 Jun 4;4:5165. doi: 10.1038/srep05165.
Active transport of sodium and potassium ions by Na,K-ATPase is accompanied by the enzyme conformational transition between E1 and E2 states. ATP and ADP bind to Na,K-ATPase in the E1 conformation with similar affinity but the properties of enzyme in complexes with these nucleotides are different. We have studied thermodynamics of Na,K-ATPase binding with adenine nucleotides at different temperatures using isothermal titration calorimetry. Our data indicate that β-phosphate is involved in complex formation by increasing the affinity of adenine nucleotides to Na,K-ATPase by an order of magnitude, while γ-phosphate does not affect it. ATP binding to Na,K-ATPase in contrast to ADP binding generates a structural transition in the enzyme, which is consistent with the movement of a significant portion of the surface area to a solvent-protected state. We propose that ATP binding leads to convergence of the nucleotide-binding and phosphorylation domains transferring the enzyme from the "E1-open" to "E1-closed" conformation ready for phosphorylation.
钠钾ATP酶对钠和钾离子的主动转运伴随着酶在E1和E2状态之间的构象转变。ATP和ADP以相似的亲和力结合处于E1构象的钠钾ATP酶，但酶与这些核苷酸形成的复合物的性质不同。我们使用等温滴定量热法研究了不同温度下钠钾ATP酶与腺嘌呤核苷酸结合的热力学。我们的数据表明，β-磷酸通过将腺嘌呤核苷酸对钠钾ATP酶的亲和力提高一个数量级参与复合物的形成，而γ-磷酸则不影响。与ADP结合相比，ATP与钠钾ATP酶的结合会在酶中产生结构转变，这与大部分表面积向溶剂保护状态的移动一致。我们提出，ATP结合导致核苷酸结合域和磷酸化域汇聚，使酶从“E1开放”构象转变为“E1封闭”构象，为磷酸化做好准备。
