Reductive nitrosylation of Methanosarcina acetivorans protoglobin: A comparative study

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• 作者：Paolo Ascenzi^a ; ^b ; ^{ascenzi@uniroma3.it} ; Alessandra Pesce^c ; Marco Nardini^d ; Martino Bolognesi^d ; Chiara Ciaccio^e ; ^f ; Massimo Coletta^e ; ^f ; Sylvia Dewilde^g
• 关键词：Hb ; hemoglobin ; HPX&ndash ; heme&ndash ; Fe ; hemopexin&ndash ; heme&ndash ; Fe ; HSA&ndash ; heme&ndash ; Fe ; human serum heme&ndash ; albumin ; Lb ; leghemoglobin ; MaPgb ; Methanosarcina acetivorans protoglobin ; MaPgb(III) ; ferric MaPgb ; MaPgb(III)&ndash ; NO ; nitrosylated
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2013
• 出版时间：25 January, 2013
• 年：2013
• 卷：430
• 期：4
• 页码：1301-1305
• 全文大小：343 K

文摘

Methanosarcina acetivorans is a strictly anaerobic non-motile methane-producing Archaea expressing protoglobin (Pgb) which might either facilitate O₂ detoxification or act as a CO sensor/supplier in methanogenesis. Unusually, M. acetivorans Pgb (MaPgb) binds preferentially O₂ rather than CO and displays anticooperativity in ligand binding. Here, kinetics and/or thermodynamics of ferric and ferrous MaPgb (MaPgb(III) and MaPgb(II), respectively) nitrosylation are reported. Data were obtained between pH 7.2 and 9.5, at 22.0 ¡ãC. Addition of NO to MaPgb(III) leads to the transient formation of MaPgb(III)-NO in equilibrium with MaPgb(II)-NO⁺. In turn, MaPgb(II)-NO⁺ is converted to MaPgb(II) by OH^?-based catalysis. Then, MaPgb(II) binds NO very rapidly leading to MaPgb(II)-NO. The rate-limiting step for reductive nitrosylation of MaPgb(III) is represented by the OH^?-mediated reduction of MaPgb(II)-NO⁺ to MaPgb(II). Present results highlight the potential role of MaPgb in scavenging of reactive nitrogen and oxygen species.