Abstract
The aceA and glcB genes, encoding isocitrate lyase (ICL) and malate synthase, respectively, are not in an operon in many bacteria, including Pseudomonas aeruginosa, unlike in Escherichia coli. Here, we show that expression of aceA in P. aeruginosa is specifically upregulated under H2O2-induced oxidative stress and under iron-limiting conditions. In contrast, the addition of exogenous redox active compounds or antibiotics increases the expression of glcB. The transcriptional start sites of aceA under iron-limiting conditions and in the presence of iron were found to be identical by 5′ RACE. Interestingly, the enzymatic activities of ICL and isocitrate dehydrogenase had opposite responses under different iron conditions, suggesting that the glyoxylate shunt (GS) might be important under iron-limiting conditions. Remarkably, the intracellular iron concentration was lower while the iron demand was higher in the GS-activated cells growing on acetate compared to cells growing on glucose. Absence of GS dysregulated iron homeostasis led to changes in the cellular iron pool, with higher intracellular chelatable iron levels. In addition, GS mutants were found to have higher cytochrome c oxidase activity on iron-supplemented agar plates of minimal media, which promoted the growth of the GS mutants. However, deletion of the GS genes resulted in higher sensitivity to a high concentration of H2O2, presumably due to iron-mediated killing. In conclusion, the GS system appears to be tightly linked to iron homeostasis in the promotion of P. aeruginosa survival under oxidative stress.
| Original language | English |
|---|---|
| Article number | 000623 |
| Pages (from-to) | 587-599 |
| Number of pages | 13 |
| Journal | Microbiology (United Kingdom) |
| Volume | 164 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 2018 Apr 1 |
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Keywords
- Bacteria
- Gene expression
- Glyoxylate bypass
- Iron
- Oxidative stress
- TCA cycle
ASJC Scopus subject areas
- Microbiology
Cite this
Lack of glyoxylate shunt dysregulates iron homeostasis in pseudomonas aeruginosa. / Ha, Sunhee; Shin, Bora; Park, Woojun.
In: Microbiology (United Kingdom), Vol. 164, No. 4, 000623, 01.04.2018, p. 587-599.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Lack of glyoxylate shunt dysregulates iron homeostasis in pseudomonas aeruginosa
AU - Ha, Sunhee
AU - Shin, Bora
AU - Park, Woojun
PY - 2018/4/1
Y1 - 2018/4/1
N2 - The aceA and glcB genes, encoding isocitrate lyase (ICL) and malate synthase, respectively, are not in an operon in many bacteria, including Pseudomonas aeruginosa, unlike in Escherichia coli. Here, we show that expression of aceA in P. aeruginosa is specifically upregulated under H2O2-induced oxidative stress and under iron-limiting conditions. In contrast, the addition of exogenous redox active compounds or antibiotics increases the expression of glcB. The transcriptional start sites of aceA under iron-limiting conditions and in the presence of iron were found to be identical by 5′ RACE. Interestingly, the enzymatic activities of ICL and isocitrate dehydrogenase had opposite responses under different iron conditions, suggesting that the glyoxylate shunt (GS) might be important under iron-limiting conditions. Remarkably, the intracellular iron concentration was lower while the iron demand was higher in the GS-activated cells growing on acetate compared to cells growing on glucose. Absence of GS dysregulated iron homeostasis led to changes in the cellular iron pool, with higher intracellular chelatable iron levels. In addition, GS mutants were found to have higher cytochrome c oxidase activity on iron-supplemented agar plates of minimal media, which promoted the growth of the GS mutants. However, deletion of the GS genes resulted in higher sensitivity to a high concentration of H2O2, presumably due to iron-mediated killing. In conclusion, the GS system appears to be tightly linked to iron homeostasis in the promotion of P. aeruginosa survival under oxidative stress.
AB - The aceA and glcB genes, encoding isocitrate lyase (ICL) and malate synthase, respectively, are not in an operon in many bacteria, including Pseudomonas aeruginosa, unlike in Escherichia coli. Here, we show that expression of aceA in P. aeruginosa is specifically upregulated under H2O2-induced oxidative stress and under iron-limiting conditions. In contrast, the addition of exogenous redox active compounds or antibiotics increases the expression of glcB. The transcriptional start sites of aceA under iron-limiting conditions and in the presence of iron were found to be identical by 5′ RACE. Interestingly, the enzymatic activities of ICL and isocitrate dehydrogenase had opposite responses under different iron conditions, suggesting that the glyoxylate shunt (GS) might be important under iron-limiting conditions. Remarkably, the intracellular iron concentration was lower while the iron demand was higher in the GS-activated cells growing on acetate compared to cells growing on glucose. Absence of GS dysregulated iron homeostasis led to changes in the cellular iron pool, with higher intracellular chelatable iron levels. In addition, GS mutants were found to have higher cytochrome c oxidase activity on iron-supplemented agar plates of minimal media, which promoted the growth of the GS mutants. However, deletion of the GS genes resulted in higher sensitivity to a high concentration of H2O2, presumably due to iron-mediated killing. In conclusion, the GS system appears to be tightly linked to iron homeostasis in the promotion of P. aeruginosa survival under oxidative stress.
KW - Bacteria
KW - Gene expression
KW - Glyoxylate bypass
KW - Iron
KW - Oxidative stress
KW - TCA cycle
UR - http://www.scopus.com/inward/record.url?scp=85045152131&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85045152131&partnerID=8YFLogxK
U2 - 10.1099/mic.0.000623
DO - 10.1099/mic.0.000623
M3 - Article
C2 - 29465342
AN - SCOPUS:85045152131
VL - 164
SP - 587
EP - 599
JO - Microbiology (United Kingdom)
JF - Microbiology (United Kingdom)
SN - 1350-0872
IS - 4
M1 - 000623
ER -