Crystal Structure Analysis of the Repair of Iron Centers Protein YtfE and Its Interaction with NO

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• 作者：Dr. Feng-Chun Lo ; Chang-Chih Hsieh ; Dr. Manuel Maestre-Reyna ; Prof. Chin-Yu Chen ; Dr. Tzu-Ping Ko ; Prof. Yih-Chern Horng ; Yei-Chen Lai ; Prof. Yun-Wei Chiang ; Chih-Mao Chou ; Cheng-Hung Chiang ; Prof. Wei-Ning Huang ; Dr. Yi-Hung Lin ; Prof. D. Scott Bohle and Prof. Wen-Feng Liaw
• 刊名：Chemistry - A European Journal
• 出版年：2016
• 出版时间：July 4, 2016
• 年：2016
• 卷：22
• 期：28
• 页码：9768-9776
• 全文大小：2614K
• ISSN：1521-3765

文摘

Molecular mechanisms underlying the repair of nitrosylated [Fe–S] clusters by the microbial protein YtfE remain poorly understood. The X-ray crystal structure of YtfE, in combination with EPR, magnetic circular dichroism (MCD), UV, and ¹⁷O-labeling electron spin echo envelope modulation measurements, show that each iron of the oxo-bridged Fe^II–Fe^III diiron core is coordinatively unsaturated with each iron bound to two bridging carboxylates and two terminal histidines in addition to an oxo-bridge. Structural analysis reveals that there are two solvent-accessible tunnels, both of which converge to the diiron center and are critical for capturing substrates. The reactivity of the reduced-form Fe^II–Fe^II YtfE toward nitric oxide demonstrates that the prerequisite for N₂O production requires the two iron sites to be nitrosylated simultaneously. Specifically, the nitrosylation of the two iron sites prior to their reductive coupling to produce N₂O is cooperative. This result suggests that, in addition to any repair of iron centers (RIC) activity, YtfE acts as an NO-trapping scavenger to promote the NO to N₂O transformation under low NO flux, which precedes nitrosative stress.