Arachidonic acid stress impacts pneumococcal fatty acid homeostasis

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  (Published version)

Date

2018

Authors

Eijkelkamp, B.
Begg, S.
Pederick, V.
Trapetti, C.
Gregory, M.
Whittall, J.
Paton, J.
McDevitt, C.

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Journal Title

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Journal article

Citation

Frontiers in Microbiology, 2018; 9(MAY):813-1-813-12

Statement of Responsibility

Bart A. Eijkelkamp, Stephanie L. Begg, Victoria G. Pederick, Claudia Trapetti, Melissa K. Gregory, Jonathan J. Whittall, James C. Paton and Christopher A. McDevitt

Conference Name

DOI

10.3389/fmicb.2018.00813

Abstract

Free fatty acids hold dual roles during infection, serving to modulate the host immune response while also functioning directly as antimicrobials. Of particular importance are the long chain polyunsaturated fatty acids, which are not commonly found in bacterial organisms, that have been proposed to have antibacterial roles. Arachidonic acid (AA) is a highly abundant long chain polyunsaturated fatty acid and we examined its effect upon Streptococcus pneumoniae. Here, we observed that in a murine model of S. pneumoniae infection the concentration of AA significantly increases in the blood. The impact of AA stress upon the pathogen was then assessed by a combination of biochemical, biophysical and microbiological assays. In vitro bacterial growth and intra-macrophage survival assays revealed that AA has detrimental effects on pneumococcal fitness. Subsequent analyses demonstrated that AA exerts antimicrobial activity via insertion into the pneumococcal membrane, although this did not increase the susceptibility of the bacterium to antibiotic, oxidative or metal ion stress. Transcriptomic profiling showed that AA treatment also resulted in a dramatic down-regulation of the genes involved in fatty acid biosynthesis, in addition to impacts on other metabolic processes, such as carbon-source utilization. Hence, these data reveal that AA has two distinct mechanisms of perturbing the pneumococcal membrane composition. Collectively, this work provides a molecular basis for the antimicrobial contribution of AA to combat pneumococcal infections.

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Published: 11 May 2018

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Copyright © 2018 Eijkelkamp, Begg, Pederick, Trapetti, Gregory,Whittall, Paton and McDevitt. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

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Grant ID

http://purl.org/au-research/grants/nhmrc/1080784
 http://purl.org/au-research/grants/nhmrc/1122582
 http://purl.org/au-research/grants/nhmrc/1071659
 http://purl.org/au-research/grants/arc/DP150104515
 http://purl.org/au-research/grants/arc/DP170102102
 http://purl.org/au-research/grants/nhmrc/1142695
 http://purl.org/au-research/grants/arc/FT170100006

Published Version

https://doi.org/10.3389/fmicb.2018.00813

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Persistent link to this record

http://hdl.handle.net/2440/112399