Pseudomonas fluorescens orchestrates a fine metabolic-balancing act to counter aluminium toxicity.
Aluminium (Al), an environmental toxin, is known to disrupt cellular functions by perturbing iron (Fe) homeostasis. However, Fe is essential for such metabolic processes as the tricarboxylic acid (TCA) cycle and oxidative phosphorylation, the two pivotal networks that mediate ATP production during aerobiosis. To counter the Fe conundrum induced by Al toxicity, Pseudomonas fluorescens utilizes isocitrate lyase and isocitrate dehydrogenase-NADP dependent to metabolize citrate when confronted with an ineffective aconitase provoked by Al stress. By invoking fumarase C, a hydratase devoid of Fe, this microbe is able to generate essential metabolites. To compensate for the severely diminished enzymes like Complex I, Complex II and Complex IV, the upregulation of a H(2)O-generating NADH oxidase enables the metabolism of citrate, the sole carbon source via a modified TCA cycle. The overexpression of succinyl-CoA synthetase affords an effective route to ATP production by substrate-level phosphorylation in the absence of O(2). This fine metabolic balance enables P. fluorescens to survive the dearth of bioavailable Fe triggered by an Al environment, a feature that may have potential applications in bioremediation technologies.
Lemire
Joseph
J
Department of Chemistry and Biochemistry, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON, Canada, P3E 2C6.
Mailloux
Ryan
R
Auger
Christopher
C
Whalen
Daniel
D
Appanna
Vasu D
VD
D000255:Adenosine Triphosphate / Q000378:metabolism; D000535:Aluminum / Q000633:toxicity*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D019343:Citric Acid / Q000378:metabolism; D002952:Citric Acid Cycle / Q000502:physiology; D004579:Electron Transport / Q000502:physiology; D006706:Homeostasis; D019746:Intramolecular Oxidoreductases / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000378:metabolism; D007521:Isocitrate Dehydrogenase / Q000378:metabolism; D007522:Isocitrate Lyase / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D011551:Pseudomonas fluorescens / Q000187:drug effects* / Q000378:metabolism*; D013389:Succinate-CoA Ligases / Q000378:metabolism
D001426:Bacterial Proteins; D007506:Iron-Sulfur Proteins; D009243:NAD; D019343:Citric Acid; D000255:Adenosine Triphosphate; D000535:Aluminum; D007501:Iron; D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+); D007522:Isocitrate Lyase; D019746:Intramolecular Oxidoreductases; C048474:oxaloacetate tautomerase; D013389:Succinate-CoA Ligases