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. 1997 Oct;115(2):519–526. doi: 10.1104/pp.115.2.519

Identification of a Transport Mechanism for NH4+ in the Symbiosome Membrane of Pea Root Nodules.

P Mouritzen 1, L Rosendahl 1
PMCID: PMC158510  PMID: 12223820

Abstract

Symbiosome membrane vesicles, facing bacteroid-side-out, were purified from pea (Pisum sativum L.) root nodules and used to study NH4+ transport across the membrane by recording vesicle uptake of the NH4+ analog [14C]methylamine (MA). Membrane potentials ([delta][psi]) were imposed on the vesicles using K+ concentration gradients and valinomycin, and the size of the imposed [delta][psi] was determined by measuring vesicle uptake of [14C]tetraphenylphosphonium. Vesicle uptake of MA was driven by a negative [delta][psi] and was stimulated by a low extravesicular pH. Protonophore-induced collapse of the pH gradient indicated that uptake of MA was not related to the presence of a pH gradient. The MA-uptake mechanism appeared to have a large capacity for transport, and saturation was not observed at MA concentrations in the range of 25 [mu]M to 150 mM. MA uptake could be inhibited by NH4+, which indicates that NH4+ and MA compete for the same uptake mechanism. The observed fluxes suggest that voltage-driven channels are operating in the symbiosome membrane and that these are capable of transporting NH4+ at high rates from the bacteroid side of the membrane to the plant cytosol. The pH of the symbiosome space is likely to be involved in regulation of the flux.

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Selected References

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  1. Bradford M. M. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976 May 7;72:248–254. doi: 10.1016/0003-2697(76)90527-3. [DOI] [PubMed] [Google Scholar]
  2. Huang J. W., Grunes D. L., Kochian L. V. Voltage-dependent Ca2+ influx into right-side-out plasma membrane vesicles isolated from wheat roots: characterization of a putative Ca2+ channel. Proc Natl Acad Sci U S A. 1994 Apr 12;91(8):3473–3477. doi: 10.1073/pnas.91.8.3473. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Ninnemann O., Jauniaux J. C., Frommer W. B. Identification of a high affinity NH4+ transporter from plants. EMBO J. 1994 Aug 1;13(15):3464–3471. doi: 10.1002/j.1460-2075.1994.tb06652.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. O'Brian M. R., Maier R. J. Molecular aspects of the energetics of nitrogen fixation in Rhizobium-legume symbioses. Biochim Biophys Acta. 1989 May 30;974(3):229–246. doi: 10.1016/s0005-2728(89)80239-7. [DOI] [PubMed] [Google Scholar]
  5. Palmgren M. G., Askerlund P., Fredrikson K., Widell S., Sommarin M., Larsson C. Sealed inside-out and right-side-out plasma membrane vesicles : optimal conditions for formation and separation. Plant Physiol. 1990 Apr;92(4):871–880. doi: 10.1104/pp.92.4.871. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Peña A., Pardo J. P., Ramírez J. Early metabolic effects and mechanism of ammonium transport in yeast. Arch Biochem Biophys. 1987 Mar;253(2):431–438. doi: 10.1016/0003-9861(87)90196-2. [DOI] [PubMed] [Google Scholar]
  7. Pressman B. C. Biological applications of ionophores. Annu Rev Biochem. 1976;45:501–530. doi: 10.1146/annurev.bi.45.070176.002441. [DOI] [PubMed] [Google Scholar]
  8. Rottenberg H. Proton electrochemical potential gradient in vesicles, organelles, and prokaryotic cells. Methods Enzymol. 1989;172:63–84. doi: 10.1016/s0076-6879(89)72008-5. [DOI] [PubMed] [Google Scholar]
  9. Schachtman D. P., Schroeder J. I. Structure and transport mechanism of a high-affinity potassium uptake transporter from higher plants. Nature. 1994 Aug 25;370(6491):655–658. doi: 10.1038/370655a0. [DOI] [PubMed] [Google Scholar]
  10. Schroeder J. I., Ward J. M., Gassmann W. Perspectives on the physiology and structure of inward-rectifying K+ channels in higher plants: biophysical implications for K+ uptake. Annu Rev Biophys Biomol Struct. 1994;23:441–471. doi: 10.1146/annurev.bb.23.060194.002301. [DOI] [PubMed] [Google Scholar]
  11. Streeter J. G. Estimation of ammonium concentration in the cytosol of soybean nodules. Plant Physiol. 1989 Jul;90(3):779–782. doi: 10.1104/pp.90.3.779. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Szafran M. M., Haaker H. Properties of the Peribacteroid Membrane ATPase of Pea Root Nodules and Its Effect on the Nitrogenase Activity. Plant Physiol. 1995 Jul;108(3):1227–1232. doi: 10.1104/pp.108.3.1227. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Udvardi M. K., Day D. A. Ammonia (C-Methylamine) Transport across the Bacteroid and Peribacteroid Membranes of Soybean Root Nodules. Plant Physiol. 1990 Sep;94(1):71–76. doi: 10.1104/pp.94.1.71. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Udvardi M. K., Day D. A. Electrogenic ATPase Activity on the Peribacteroid Membrane of Soybean (Glycine max L.) Root Nodules. Plant Physiol. 1989 Jul;90(3):982–987. doi: 10.1104/pp.90.3.982. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Udvardi Michael K., Day David A. METABOLITE TRANSPORT ACROSS SYMBIOTIC MEMBRANES OF LEGUME NODULES. Annu Rev Plant Physiol Plant Mol Biol. 1997 Jun;48(NaN):493–523. doi: 10.1146/annurev.arplant.48.1.493. [DOI] [PubMed] [Google Scholar]
  16. Véry A. A., Gaymard F., Bosseux C., Sentenac H., Thibaud J. B. Expression of a cloned plant K+ channel in Xenopus oocytes: analysis of macroscopic currents. Plant J. 1995 Feb;7(2):321–332. doi: 10.1046/j.1365-313x.1995.7020321.x. [DOI] [PubMed] [Google Scholar]

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