Isolation and immunocytochemical location of the nitrite-oxidizing system in Nitrospira moscoviensis

E. Spieck, Silke Ehrich, Jens Aamand, Eberhard Bock

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61 Citations (Scopus)

Abstract

A membrane-associated nitrite-oxidizing system of Nitrospira moscoviensis was isolated from heat-treated membranes. The four major proteins of the enzyme fraction had apparent molecular masses of 130, 62, 46, and 29 kDa, respectively. The nitrite-oxidizing activity was dependent on the presence of molybdenum. In contrast to the nitrite oxidoreductase of Nitrobacter hamburgensis X14, the activity of the nitrite-oxidizing system of Ns. moscoviensis increased when solubilized by heat treatment. Electron microscopy of the purified enzyme revealed uniform particles with a size of approximately 7 x 9 nm. SDS-immunoblotting analysis of crude extracts showed that the monoclonal antibodies Hyb 153-3, which recognize the β-subunit of the nitrite oxidoreductase from Nitrobacter, reacted with a protein of 50 kDa in Ns. moscoviensis. This protein corresponded to the protein of 46 kDa of the purified enzyme and contained a b-type cytochrome. Using electron microscopic immunocytochemistry and the monoclonal antibodies Hyb 153-3, the nitrite-oxidizing system of Ns. moscoviensis was shown to be located in the periplasmic space. Here a periodic arrangement of membrane-associated particles was found on the outside of the cytoplasmic membrane in the form of a hexagonal pattern. It is supposed that these particles represent the nitrite-oxidizing system in Nitrospira.

Original languageEnglish
Pages (from-to)225-230
Number of pages6
JournalArchives of Microbiology
Volume169
Issue number3
DOIs
Publication statusPublished - Feb 1998

Keywords

  • Hexagonal pattern
  • Membrane-associated enzyme
  • Monoclonal antibodies
  • Nitrite-oxidizing system
  • Nitrospira moscoviensis
  • Periplasmic space
  • Post-embedding labeling

Programme Area

  • Programme Area 2: Water Resources

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