Nitrite-reductase and peroxynitrite isomerization activities of Methanosarcina acetivorans protoglobin.

Within the globin superfamily, protoglobins (Pgb) belong phylogenetically to the same cluster of two-domain globin-coupled sensors and single-domain sensor globins. Multiple functional roles have been postulated for Methanosarcina acetivorans Pgb (Ma-Pgb), since the detoxification of reactive nitrog...

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Autores principales:	Paolo Ascenzi, Loris Leboffe, Alessandra Pesce, Chiara Ciaccio, Diego Sbardella, Martino Bolognesi, Massimo Coletta
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2014
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/1b45c7a96e9140c193bf845f20452f81
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spelling	oai:doaj.org-article:1b45c7a96e9140c193bf845f20452f812021-11-18T08:19:23ZNitrite-reductase and peroxynitrite isomerization activities of Methanosarcina acetivorans protoglobin.1932-620310.1371/journal.pone.0095391https://doaj.org/article/1b45c7a96e9140c193bf845f20452f812014-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/24827820/?tool=EBIhttps://doaj.org/toc/1932-6203Within the globin superfamily, protoglobins (Pgb) belong phylogenetically to the same cluster of two-domain globin-coupled sensors and single-domain sensor globins. Multiple functional roles have been postulated for Methanosarcina acetivorans Pgb (Ma-Pgb), since the detoxification of reactive nitrogen and oxygen species might co-exist with enzymatic activity(ies) to facilitate the conversion of CO to methane. Here, the nitrite-reductase and peroxynitrite isomerization activities of the CysE20Ser mutant of Ma-Pgb (Ma-Pgb) are reported and analyzed in parallel with those of related heme-proteins. Kinetics of nitrite-reductase activity of ferrous Ma-Pgb (Ma-Pgb-Fe(II)) is biphasic and values of the second-order rate constant for the reduction of NO2- to NO and the concomitant formation of nitrosylated Ma-Pgb-Fe(II) (Ma-Pgb-Fe(II)-NO) are k(app1)= 9.6 ± 0.2 M(-1) s(-1) and k(app2) = 1.2 ± 0.1 M(-1) s(-1) (at pH 7.4 and 20 °C). The k(app1) and k(app2) values increase by about one order of magnitude for each pH unit decrease, between pH 8.3 and 6.2, indicating that the reaction requires one proton. On the other hand, kinetics of peroxynitrite isomerization catalyzed by ferric Ma-Pgb (Ma-Pgb-Fe(III)) is monophasic and values of the second order rate constant for peroxynitrite isomerization by Ma-Pgb-Fe(III) and of the first order rate constant for the spontaneous conversion of peroxynitrite to nitrate are h(app) = 3.8 × 10(4 )M(-1) s(-1) and h0 = 2.8 × 10(-1) s(-1) (at pH 7.4 and 20 °C). The pH-dependence of hon and h0 values reflects the acid-base equilibrium of peroxynitrite (pKa = 6.7 and 6.9, respectively; at 20 °C), indicating that HOONO is the species that reacts preferentially with the heme-Fe(III) atom. These results highlight the potential role of Pgbs in the biosynthesis and scavenging of reactive nitrogen and oxygen species.Paolo AscenziLoris LeboffeAlessandra PesceChiara CiaccioDiego SbardellaMartino BolognesiMassimo ColettaPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 9, Iss 5, p e95391 (2014)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Paolo Ascenzi Loris Leboffe Alessandra Pesce Chiara Ciaccio Diego Sbardella Martino Bolognesi Massimo Coletta Nitrite-reductase and peroxynitrite isomerization activities of Methanosarcina acetivorans protoglobin.
description	Within the globin superfamily, protoglobins (Pgb) belong phylogenetically to the same cluster of two-domain globin-coupled sensors and single-domain sensor globins. Multiple functional roles have been postulated for Methanosarcina acetivorans Pgb (Ma-Pgb), since the detoxification of reactive nitrogen and oxygen species might co-exist with enzymatic activity(ies) to facilitate the conversion of CO to methane. Here, the nitrite-reductase and peroxynitrite isomerization activities of the CysE20Ser mutant of Ma-Pgb (Ma-Pgb) are reported and analyzed in parallel with those of related heme-proteins. Kinetics of nitrite-reductase activity of ferrous Ma-Pgb (Ma-Pgb-Fe(II)) is biphasic and values of the second-order rate constant for the reduction of NO2- to NO and the concomitant formation of nitrosylated Ma-Pgb-Fe(II) (Ma-Pgb-Fe(II)-NO) are k(app1)= 9.6 ± 0.2 M(-1) s(-1) and k(app2) = 1.2 ± 0.1 M(-1) s(-1) (at pH 7.4 and 20 °C). The k(app1) and k(app2) values increase by about one order of magnitude for each pH unit decrease, between pH 8.3 and 6.2, indicating that the reaction requires one proton. On the other hand, kinetics of peroxynitrite isomerization catalyzed by ferric Ma-Pgb (Ma-Pgb-Fe(III)) is monophasic and values of the second order rate constant for peroxynitrite isomerization by Ma-Pgb-Fe(III) and of the first order rate constant for the spontaneous conversion of peroxynitrite to nitrate are h(app) = 3.8 × 10(4 )M(-1) s(-1) and h0 = 2.8 × 10(-1) s(-1) (at pH 7.4 and 20 °C). The pH-dependence of hon and h0 values reflects the acid-base equilibrium of peroxynitrite (pKa = 6.7 and 6.9, respectively; at 20 °C), indicating that HOONO is the species that reacts preferentially with the heme-Fe(III) atom. These results highlight the potential role of Pgbs in the biosynthesis and scavenging of reactive nitrogen and oxygen species.
format	article
author	Paolo Ascenzi Loris Leboffe Alessandra Pesce Chiara Ciaccio Diego Sbardella Martino Bolognesi Massimo Coletta
author_facet	Paolo Ascenzi Loris Leboffe Alessandra Pesce Chiara Ciaccio Diego Sbardella Martino Bolognesi Massimo Coletta
author_sort	Paolo Ascenzi
title	Nitrite-reductase and peroxynitrite isomerization activities of Methanosarcina acetivorans protoglobin.
title_short	Nitrite-reductase and peroxynitrite isomerization activities of Methanosarcina acetivorans protoglobin.
title_full	Nitrite-reductase and peroxynitrite isomerization activities of Methanosarcina acetivorans protoglobin.
title_fullStr	Nitrite-reductase and peroxynitrite isomerization activities of Methanosarcina acetivorans protoglobin.
title_full_unstemmed	Nitrite-reductase and peroxynitrite isomerization activities of Methanosarcina acetivorans protoglobin.
title_sort	nitrite-reductase and peroxynitrite isomerization activities of methanosarcina acetivorans protoglobin.
publisher	Public Library of Science (PLoS)
publishDate	2014
url	https://doaj.org/article/1b45c7a96e9140c193bf845f20452f81
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Nitrite-reductase and peroxynitrite isomerization activities of Methanosarcina acetivorans protoglobin.

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