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Borrelia burgdorferi membranes are the primary targets of reactive oxygen species.

Boylan JA, Lawrence KA, Downey JS, Gherardini FC - Mol. Microbiol. (2008)

Bottom Line: Because Borrelia burgdorferi contains no intracellular iron, DNA is most likely not a major target for ROS via Fenton reaction.Fatty acid analysis of cells treated with lipoxidase indicated that host-derived linoleic acid had been dramatically reduced (50-fold) in these cells, with a corresponding increase in the levels of malondialdehyde by-product (fourfold).These data suggest that B. burgdorferi membrane lipids are targets for attack by ROS encountered in the various stages of the infective cycle.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories, 903 S 4th Street, Hamilton, MT 59840, USA.

ABSTRACT
Spirochetes living in an oxygen-rich environment or when challenged by host immune cells are exposed to reactive oxygen species (ROS). These species can harm/destroy cysteinyl residues, iron-sulphur clusters, DNA and polyunsaturated lipids, leading to inhibition of growth or cell death. Because Borrelia burgdorferi contains no intracellular iron, DNA is most likely not a major target for ROS via Fenton reaction. In support of this, growth of B. burgdorferi in the presence of 5 mM H(2)O(2) had no effect on the DNA mutation rate (spontaneous coumermycin A1 resistance), and cells treated with 10 mM t-butyl hydroperoxide or 10 mM H(2)O(2) show no increase in DNA damage. Unlike most bacteria, B. burgdorferi incorporates ROS-susceptible polyunsaturated fatty acids from the environment into their membranes. Analysis of lipoxidase-treated B. burgdorferi cells by Electron Microscopy showed significant irregularities indicative of membrane damage. Fatty acid analysis of cells treated with lipoxidase indicated that host-derived linoleic acid had been dramatically reduced (50-fold) in these cells, with a corresponding increase in the levels of malondialdehyde by-product (fourfold). These data suggest that B. burgdorferi membrane lipids are targets for attack by ROS encountered in the various stages of the infective cycle.

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Treatment of B. burgdorferi cells with lipoxidase causes membrane damage. B. burgdorferi B31A3 cells were grown (A) anaerobically or (B) microaerobically to a cell density of ∼5 × 107 cells ml−1. The microaerobic culture was split and one half exposed to (C) lipoxidase for 4 h. The cells were fixed with Karnovsky's phosphate and stained with 1% ammonium molybdate. Samples were examined and photographed using a Hitachi electron microscope.
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fig06: Treatment of B. burgdorferi cells with lipoxidase causes membrane damage. B. burgdorferi B31A3 cells were grown (A) anaerobically or (B) microaerobically to a cell density of ∼5 × 107 cells ml−1. The microaerobic culture was split and one half exposed to (C) lipoxidase for 4 h. The cells were fixed with Karnovsky's phosphate and stained with 1% ammonium molybdate. Samples were examined and photographed using a Hitachi electron microscope.

Mentions: To further demonstrate Borrelia membrane damage, B. burgdorferi B31A3 cells were grown under anaerobic and microaerobic conditions and visualized by negative stain using an electron microscope. Additionally, cells grown under microaerobic conditions were treated with 250 mg of lipoxidase and visualized by Electron Microscopy. Intact membranes were observed in cultures of B31A3 grown under anaerobic and microaerobic conditions (Fig. 6A and B respectively). However, in cultures treated with lipoxidase (Fig. 6C), a significant number of membrane blebs were seen surrounding the spirochetes, indicating membrane damage. Taken together, these data indicated that Borrelia membranes were a target for oxidative stress.


Borrelia burgdorferi membranes are the primary targets of reactive oxygen species.

Boylan JA, Lawrence KA, Downey JS, Gherardini FC - Mol. Microbiol. (2008)

Treatment of B. burgdorferi cells with lipoxidase causes membrane damage. B. burgdorferi B31A3 cells were grown (A) anaerobically or (B) microaerobically to a cell density of ∼5 × 107 cells ml−1. The microaerobic culture was split and one half exposed to (C) lipoxidase for 4 h. The cells were fixed with Karnovsky's phosphate and stained with 1% ammonium molybdate. Samples were examined and photographed using a Hitachi electron microscope.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2327290&req=5

fig06: Treatment of B. burgdorferi cells with lipoxidase causes membrane damage. B. burgdorferi B31A3 cells were grown (A) anaerobically or (B) microaerobically to a cell density of ∼5 × 107 cells ml−1. The microaerobic culture was split and one half exposed to (C) lipoxidase for 4 h. The cells were fixed with Karnovsky's phosphate and stained with 1% ammonium molybdate. Samples were examined and photographed using a Hitachi electron microscope.
Mentions: To further demonstrate Borrelia membrane damage, B. burgdorferi B31A3 cells were grown under anaerobic and microaerobic conditions and visualized by negative stain using an electron microscope. Additionally, cells grown under microaerobic conditions were treated with 250 mg of lipoxidase and visualized by Electron Microscopy. Intact membranes were observed in cultures of B31A3 grown under anaerobic and microaerobic conditions (Fig. 6A and B respectively). However, in cultures treated with lipoxidase (Fig. 6C), a significant number of membrane blebs were seen surrounding the spirochetes, indicating membrane damage. Taken together, these data indicated that Borrelia membranes were a target for oxidative stress.

Bottom Line: Because Borrelia burgdorferi contains no intracellular iron, DNA is most likely not a major target for ROS via Fenton reaction.Fatty acid analysis of cells treated with lipoxidase indicated that host-derived linoleic acid had been dramatically reduced (50-fold) in these cells, with a corresponding increase in the levels of malondialdehyde by-product (fourfold).These data suggest that B. burgdorferi membrane lipids are targets for attack by ROS encountered in the various stages of the infective cycle.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories, 903 S 4th Street, Hamilton, MT 59840, USA.

ABSTRACT
Spirochetes living in an oxygen-rich environment or when challenged by host immune cells are exposed to reactive oxygen species (ROS). These species can harm/destroy cysteinyl residues, iron-sulphur clusters, DNA and polyunsaturated lipids, leading to inhibition of growth or cell death. Because Borrelia burgdorferi contains no intracellular iron, DNA is most likely not a major target for ROS via Fenton reaction. In support of this, growth of B. burgdorferi in the presence of 5 mM H(2)O(2) had no effect on the DNA mutation rate (spontaneous coumermycin A1 resistance), and cells treated with 10 mM t-butyl hydroperoxide or 10 mM H(2)O(2) show no increase in DNA damage. Unlike most bacteria, B. burgdorferi incorporates ROS-susceptible polyunsaturated fatty acids from the environment into their membranes. Analysis of lipoxidase-treated B. burgdorferi cells by Electron Microscopy showed significant irregularities indicative of membrane damage. Fatty acid analysis of cells treated with lipoxidase indicated that host-derived linoleic acid had been dramatically reduced (50-fold) in these cells, with a corresponding increase in the levels of malondialdehyde by-product (fourfold). These data suggest that B. burgdorferi membrane lipids are targets for attack by ROS encountered in the various stages of the infective cycle.

Show MeSH
Related in: MedlinePlus