Reductive nitrosylation of Methanosarcina acetivorans protoglobin: a comparative study

Biochem Biophys Res Commun. 2013 Jan 25;430(4):1301-5. doi: 10.1016/j.bbrc.2012.11.122. Epub 2012 Dec 19.


Methanosarcina acetivorans is a strictly anaerobic non-motile methane-producing Archaea expressing protoglobin (Pgb) which might either facilitate O(2) detoxification or act as a CO sensor/supplier in methanogenesis. Unusually, M. acetivorans Pgb (MaPgb) binds preferentially O(2) 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 °C. 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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Archaeal Proteins / chemistry*
  • Ferric Compounds / chemistry
  • Ferrous Compounds / chemistry
  • Globins / chemistry*
  • Kinetics
  • Methanosarcina / metabolism*
  • Nitrogen / chemistry*
  • Reactive Nitrogen Species / chemistry
  • Reactive Oxygen Species / chemistry
  • Thermodynamics


  • Archaeal Proteins
  • Ferric Compounds
  • Ferrous Compounds
  • Reactive Nitrogen Species
  • Reactive Oxygen Species
  • Globins
  • Nitrogen