title: The metabolism of aluminum citrate and biosynthesis of oxalic acid in Pseudomonas fluorescens.
abstract: (13)CNMR and (1)HNMR studies revealed that aluminum citrate (Al-citrate) was metabolized intracellularly and that oxalic acid was an important product in the Al-stressed cells. This dicarboxylic acid was produced via the oxidation of glyoxylate, a precursor generated through the cleavage of isocitrate. In the control cells, citrate was biotransformed essentially with the aid of regular tricarboxylic cycle (TCA) enzymes. However, these control cells were able neither to uptake nor to metabolize Al-citrate. Al-stressed cells obtained at 38-40 h of growth showed maximal Al-citrate uptake and biotransforming activities. At least a fourfold increase in the activity of the enzyme isocitrate lyase (ICL, E. C. 4.1.3.1) has been observed in the Al-stressed cells compared with the control cells. The transport of Al-citrate was sensitive to p-dinitrophenol and sodium azide, but not to dicyclohexylcarbodiimide. Experiments with the dye 9-aminoacridine revealed that the translocation of Al-citrate led to an increase in intracellular pH. Thus, it appears that after the uptake of Al-citrate, this complex is metabolized intracellularly.
authors.affiliation: Department of Chemistry & Biochemistry, Laurentian University, Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada. vappanna@nickel.laurentian.ca
authors.forename: Vasu D
authors.initials: VD
authors.lastname: Appanna
authors.forename: Robert D
authors.initials: RD
authors.lastname: Hamel
authors.forename: Remi
authors.initials: R
authors.lastname: Lévasseur
mesh_terms: D001673:Biodegradation, Environmental; D001692:Biological Transport / Q000187:drug effects; D019343:Citric Acid / Q000378:metabolism*; D002952:Citric Acid Cycle; D004140:Dinitrophenols / Q000494:pharmacology; D006038:Glyoxylates / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007522:Isocitrate Lyase / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D019815:Oxalic Acid / Q000378:metabolism*; D010084:Oxidation-Reduction; D011551:Pseudomonas fluorescens / Q000254:growth & development / Q000378:metabolism*; D019810:Sodium Azide / Q000494:pharmacology; D013696:Temperature
chemical_list: D004140:Dinitrophenols; D006038:Glyoxylates; D019343:Citric Acid; D019810:Sodium Azide; D019815:Oxalic Acid; D007522:Isocitrate Lyase; C455846:aluminum citrate; C031150:glyoxylic acid