Presence of Host-Plasma Membrane Type H-ATPase in the Membrane Envelope Enclosing the Bacteroids in Soybean Root

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Updated: Aug 8, 2026

Polysome Purification from Soybean Symbiotic Nodules
07:02

Polysome Purification from Soybean Symbiotic Nodules

Published on: July 1, 2022

E Blumwald1, M G Fortin, P A Rea

  • 1Department of Biology, McGill University, Montreal, Quebec, Canada H3A 1B1.

Plant Physiology
|August 1, 1985
PubMed

Insights

Researchers isolated the peribacteroid membrane from soybean root nodules. Its ATPase activity is similar to plasma membrane ATPase but uniquely stimulated by ammonium, suggesting a role in nitrogen fixation.

Area of Science:

  • Plant Biology
  • Biochemistry
  • Molecular Biology

Background:

  • Soybean root nodules harbor nitrogen-fixing bacteria (bacteroids).
  • The peribacteroid membrane (PBM) encloses bacteroids within root cells.
  • Understanding PBM function is crucial for nitrogen fixation efficiency.

Purpose of the Study:

  • To develop an improved method for isolating soybean PBM.
  • To characterize the ATPase activity of PBM and compare it to plasma membrane (PM) ATPase.
  • To investigate the role of PBM ATPase in nitrogen assimilation.

Main Methods:

  • Isolation of PBM from soybean (Glycine max L.) root nodules.
  • Enzymatic assays to compare ATPase activity (vanadate sensitivity, pH optima, cation requirements).
  • Fluorescence microscopy using acridine orange to demonstrate ATP-dependent proton translocation across PBM.

Main Results:

  • PBM and PM ATPases share similarities in vanadate sensitivity, pH optima, and cation requirements.
  • PBM ATPase exhibits greater sensitivity to ammonium (NH4+) stimulation.
  • ATP-dependent proton translocation across the PBM was successfully demonstrated.

Conclusions:

  • Soybean PBM ATPase is biochemically similar to PM ATPase but has distinct regulatory properties.
  • PBM ATPase-mediated acidification of the peribacteroid space likely converts ammonia (NH3) to ammonium (NH4+).
  • This process may facilitate the efficient removal of fixed nitrogen from bacteroids to the plant.

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