Isolation of sealed plasma membrane vesicles from Phytophthora megasperma f. sp. glycinea: II. Partial characterization of Ca2+ transport and glyceollin effects

John L. Giannini, Jana S. Holt, Donald P. Briskin

Research output: Contribution to journalArticlepeer-review

Abstract

Calcium uptake was examined in sealed plasma membrane vesicles isolated from the plant pathogenic fungus, Phytophthora megasperma f. sp. glycinea. Calcium uptake was ATP-dependent and by the addition of various ionophores in the presence of ATP, it was shown that Ca2+ transport was mediated by a nH+ Ca2+ antiport. Further evidence for this antiport mechanism included Ca2+ uptake driven by an imposed pH gradient and the observation that calcium could dissipate a steady-state pH gradient across the vesicle membrane. Transport mediated by the nH+ Ca2+ antiport was optimal at pH 7.0, and demonstrated saturation kinetics for Ca2+ with a Km of about 7 μm. Glyceollin, a soybean phytoalexin, was found to inhibit Ca2+ transport consistent with its ability to increase H+ conductance. In the presence of glyceollin, calcium leakage from Phytophthora membrane vesicles also increased. This study provides basic information about calcium transport in a plant pathogenic fungus as well as demonstrating a possible mode of action of a phytoalexin.

Original languageEnglish (US)
Pages (from-to)644-649
Number of pages6
JournalArchives of Biochemistry and Biophysics
Volume266
Issue number2
DOIs
StatePublished - Nov 1 1988

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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