Adaptation of Pseudomonas fluorescens to Al-citrate: involvement of tricarboxylic acid and glyoxylate cycle enzymes and the influence of phosphate.
The degradation of Aluminum-citrate by Pseudomonas fluorescens necessitated a major restructuring of the various enzymatic activities involved in the TCA and glyoxylate cycles. While a six-fold increase in fumarase (FUM EC 4.2.1.2) activity was observed in cells subjected to Al-citrate compared to control cells, citrate synthase (CS EC 4.1.3.7) activity experienced a two-fold increase. On the other hand, in the Al-stressed cells malate synthase (MS EC 4.1.3.2) activity underwent a five-fold decrease in activity. This modulation of enzymatic activities appeared to be evoked by Al stress, as the incubation of Al-stressed cells in control media led to the complete reversal of these enzymatic profiles. These observations were further confirmed by 1H NMR and 13C NMR spectroscopy. No significant variations were observed in the activities of other glyoxylate and TCA cycle enzymes, like isocitrate lyase (ICL EC 4.1.3.1), malate dehydrogenase (MDH EC 1.1.1.37), and succinate dehydrogenase (SDH EC 1.3.99.1). This reconfiguration of the metabolic pathway appears to favour the production of a citrate-rich aluminophore that is involved in the sequestration of Al.
Appanna
Vasu D
VD
Department of Chemistry and Biochemistry, Laurentian University, Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada. Vappanna@Nickel.Laurentian.ca
Hamel
Robert
R
Mackenzie
Carrie
C
Kumar
Puja
P
Kalyuzhnyi
Sergey V
SV
D000220:Adaptation, Biological; D000535:Aluminum / Q000633:toxicity*; D001673:Biodegradation, Environmental; D002950:Citrate (si)-Synthase / Q000378:metabolism; D019343:Citric Acid / Q000378:metabolism*; D002952:Citric Acid Cycle / Q000502:physiology; D005649:Fumarate Hydratase / Q000378:metabolism; D006038:Glyoxylates / Q000378:metabolism; D007522:Isocitrate Lyase / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008291:Malate Dehydrogenase / Q000378:metabolism; D008292:Malate Synthase / Q000378:metabolism; D011551:Pseudomonas fluorescens / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D013385:Succinate Dehydrogenase / Q000378:metabolism
D006038:Glyoxylates; D019343:Citric Acid; D000535:Aluminum; D008291:Malate Dehydrogenase; D013385:Succinate Dehydrogenase; D002950:Citrate (si)-Synthase; D008292:Malate Synthase; D007522:Isocitrate Lyase; D005649:Fumarate Hydratase; C455846:aluminum citrate; C031150:glyoxylic acid