title: The effect of boron on plasma membrane electron transport and associated proton secretion by cultured carrot cells.
abstract: Plasma membrane electron transport reactions and associated proton secretion were studied in boron-deficient carrot cells. It was found that the hormone-sensitive plasma membrane NADH oxidase was inhibited by boron deficiency and that under such conditions activity could be restored by exogenous boric acid with or without 2,4-dichlorophenoxy acetic acid. Gramicidin, a channel-forming protonophore, further stimulated NADH oxidase by carrot cells. Proton secretion, associated with plasma membrane H(+)-ATPase, was also affected by boron deficiency, but not as severely as ferricyanide-generated proton secretion, reflecting plasma membrane electron transport. The addition of 1 mM boric acid and 1 microM 2,4-dichlorophenoxy acetic acid to carrot cells fully restored the H+ secretion in presence of ferricyanide. The effect of boron deficiency in cultured carrot cells can, therefore, be directly associated with cell growth through its effect on the plasma membrane NADH oxidase and H+ secretion. Ferricyanide provides a probe which activates transmembrane electron transport that is only coupled to proton release when boron is present.
authors.affiliation: Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.
authors.forename: R
authors.initials: R
authors.lastname: Barr
authors.forename: M
authors.initials: M
authors.lastname: Böttger
authors.forename: F L
authors.initials: FL
authors.lastname: Crane
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D001888:Boric Acids / Q000494:pharmacology; D001895:Boron / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D004579:Electron Transport / Q000187:drug effects; D005292:Ferricyanides / Q000494:pharmacology; D006096:Gramicidin / Q000494:pharmacology; D009097:Multienzyme Complexes / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000378:metabolism; D011522:Protons; D014675:Vegetables / Q000166:cytology / Q000378:metabolism*
chemical_list: D001888:Boric Acids; D005292:Ferricyanides; D009097:Multienzyme Complexes; D011522:Protons; C007931:hexacyanoferrate III; D006096:Gramicidin; D015084:2,4-Dichlorophenoxyacetic Acid; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D006180:Proton-Translocating ATPases; D001895:Boron; C032688:boric acid