ISSN:
1432-072X
Keywords:
Peribacteroid membrane
;
Symbiosomes
;
Grycine max
;
Nitrogen fixation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Addition of ATP to intact symbiosomes isolated from soybean nodules, resulted in generation of a membrane potential (positive inside) across the peribacteroid membrane (PBM). This energisation was monitored as oxonol fluorescence quenching. The rate of fluorescence quenching was inhibited by the inclusion of permeant anions in the reaction medium. Using this inhibition as a measure of anion uptake across the PBM, the presence of a phthalonate-sensitive dicarboxylate carrier on the PBM was confirmed. Following dissipation of the membrane potential by a permeant anion, a pH gradient, measured using [14C]methylamine uptake, was slowly established across the PBM. This ΔpH was abolished by addition of an uncoupler but was insensitive to inhibitors of bacteroid respiration. The difference in pH between the external medium and the symbiosome interior was estimated to be in the range of 1–1.6 pH units. The magnitude in planta will depend on the concentrations of ATP and permeant anions in the cytosol of the host cell.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00248711
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