Mechanistic Insight into the Nitrosylation of the [4Fe鈭?S] Cluster of WhiB-like Proteins

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• 作者：Jason C. Crack ; Laura J. Smith ; Melanie R. Stapleton ; Jamie Peck ; Nicholas J. Watmough ; Mark J. Buttner ; Roger S. Buxton ; Jeffrey Green ; Vasily S. Oganesyan ; Andrew J. Thomson ; Nick E. Le Brun
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：February 2, 2011
• 年：2011
• 卷：133
• 期：4
• 页码：1112-1121
• 全文大小：1140K
• 年卷期：v.133,no.4(February 2, 2011)
• ISSN：1520-5126

文摘

The reactivity of protein bound iron鈭抯ulfur clusters with nitric oxide (NO) is well documented, but little is known about the actual mechanism of cluster nitrosylation. Here, we report studies of members of the Wbl family of [4Fe鈭?S] containing proteins, which play key roles in regulating developmental processes in actinomycetes, including Streptomyces and Mycobacteria, and have been shown to be NO responsive. Streptomyces coelicolor WhiD and Mycobacterium tuberculosis WhiB1 react extremely rapidly with NO in a multiphasic reaction involving, remarkably, 8 NO molecules per [4Fe鈭?S] cluster. The reaction is 10⁴-fold faster than that observed with O₂ and is by far the most rapid iron鈭抯ulfur cluster nitrosylation reaction reported to date. An overall stoichiometry of [Fe₄S₄(Cys)₄]^{2鈭?/sup> + 8NO 鈫?2[FeI₂(NO)₄(Cys)₂]0 + S2鈭?/sup> + 3S0 has been established by determination of the sulfur products and their oxidation states. Kinetic analysis leads to a four-step mechanism that accounts for the observed NO dependence. DFT calculations suggest the possibility that the nitrosylation product is a novel cluster [FeI₄(NO)₈(Cys)₄]0 derived by dimerization of a pair of Roussin鈥檚 red ester (RRE) complexes.}