Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany.
Department of Structural Biology, Max Planck Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany.
Sci Adv. 2019 Apr 17;5(4):eaav4310. doi: 10.1126/sciadv.aav4310. eCollection 2019 Apr.
Anaerobic ammonium oxidation (anammox) is a major process in the biogeochemical nitrogen cycle in which nitrite and ammonium are converted to dinitrogen gas and water through the highly reactive intermediate hydrazine. So far, it is unknown how anammox organisms convert the toxic hydrazine into nitrogen and harvest the extremely low potential electrons (-750 mV) released in this process. We report the crystal structure and cryo electron microscopy structures of the responsible enzyme, hydrazine dehydrogenase, which is a 1.7 MDa multiprotein complex containing an extended electron transfer network of 192 heme groups spanning the entire complex. This unique molecular arrangement suggests a way in which the protein stores and releases the electrons obtained from hydrazine conversion, the final step in the globally important anammox process.
厌氧氨氧化（anammox）是生物地球化学氮循环中的一个主要过程，在这个过程中，亚硝酸盐和氨通过高活性中间产物联氨转化为氮气和水。到目前为止，人们还不知道 anammox 生物是如何将有毒的联氨转化为氮，并从这个过程中释放出极低的潜在电子（-750 mV）。我们报告了负责这一过程的酶——肼脱氢酶的晶体结构和低温电子显微镜结构，它是一个 1.7 MDa 的多蛋白复合物，包含 192 个血红素基团的扩展电子传递网络，横跨整个复合物。这种独特的分子排列方式表明了蛋白质从联氨转化中储存和释放电子的方式，这是全球重要的 anammox 过程的最后一步。
