固氮酶中不对称核苷酸相互作用的结构证据。

Tezcan F Akif, Kaiser Jens T, Howard James B, Rees Douglas C

Department of Chemistry and Biochemistry, University of California, San Diego , La Jolla, California 92093-0356, United States.

J Am Chem Soc. 2015 Jan 14;137(1):146-9. doi: 10.1021/ja511945e. Epub 2014 Dec 23.

The roles of ATP hydrolysis in electron-transfer (ET) reactions of the nitrogenase catalytic cycle remain obscure. Here, we present a new structure of a nitrogenase complex crystallized with MgADP and MgAMPPCP, an ATP analogue. In this structure the two nucleotides are bound asymmetrically by the Fe-protein subunits connected to the two different MoFe-protein subunits. This binding mode suggests that ATP hydrolysis and phosphate release may proceed by a stepwise mechanism. Through the associated Fe-protein conformational changes, a stepwise mechanism is anticipated to prolong the lifetime of the Fe-protein-MoFe-protein complex and, in turn, could orchestrate the sequence of intracomplex ET required for substrate reduction.

ATP水解在固氮酶催化循环的电子转移（ET）反应中的作用仍不清楚。在此，我们展示了一种与MgADP和ATP类似物MgAMPPCP结晶的固氮酶复合物的新结构。在该结构中，两个核苷酸由连接到两个不同钼铁蛋白亚基的铁蛋白亚基不对称结合。这种结合模式表明ATP水解和磷酸盐释放可能通过逐步机制进行。通过相关的铁蛋白构象变化，预计逐步机制会延长铁蛋白-钼铁蛋白复合物的寿命，进而能够协调底物还原所需的复合物内电子转移顺序。