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Bioorg Med Chem. 2016 Aug 1;24(15):3330-5. doi: 10.1016/j.bmc.2016.04.051. Epub 2016 Apr 26.

Capture of endogenously biotinylated proteins from Pseudomonas aeruginosa displays unexpected downregulation of LiuD upon iron nutrition.

Author information

1
Department of Chemical Biology, Fakultät für Biologie, Centre for Medical Biotechnology, University Duisburg-Essen, Universitätsstraße 2, 45117 Essen, Germany. Electronic address: farnusch.kaschani@uni-due.de.
2
Department of Bioengineering Sciences, Microbiology Unit, Vrije Universiteit Brussel and VIB Department of Structural Biology, Pleinlaan 2, 1050 Brussels, Belgium.
3
Plant Chemetics Lab, Max-Planck-Institute for Plant Breeding Research, Carl-von-Linné-Weg 10, 50829 Cologne, Germany.
4
Department of Chemical Biology, Fakultät für Biologie, Centre for Medical Biotechnology, University Duisburg-Essen, Universitätsstraße 2, 45117 Essen, Germany. Electronic address: markus.kaiser@uni-due.de.

Abstract

The uptake and storage but also removal of excess iron are of utmost importance to microorganisms since surplus levels of iron may lead to the formation of reactive oxygen species. Therefore, iron homeostasis is generally tightly regulated by the ferric uptake regulator (Fur), a global iron regulator acting as a transcriptional repressor. While detecting biotinylated proteins in labelling experiments, we discovered that the endogenously biotinylated protein LiuD differentially accumulated upon iron treatment. LiuD represents the α-subunit of the methylcrotonyl-CoA-carboxylase (MCCase), an enzyme from the leucine/isovalerate utilization pathway. Real-time PCR transcription analysis revealed that the observed lower levels of LiuD biotinylation could be traced back to lower LiuD protein levels via a transcriptional repression of liuABCDE expression that however does not seem to be mediated by Fur. In accordance with LiuD's role for the leucine/isovalerate utilization pathway and its protein level regulation by nutritional iron levels, we found that wild-type Pseudomonas aeruginosa did not grow in the presence of iron if the medium contained only leucine as a carbon source. Conversely, iron stimulated the growth when glucose was used as a carbon source. Our study thus demonstrates the complexities of iron-regulated bacterial growth in Pseudomonas aeruginosa.

KEYWORDS:

Affinity purification; Biotinylation; Iron homeostasis; LiuD; Pseudomonas aeruginosa

PMID:
27160053
DOI:
10.1016/j.bmc.2016.04.051
[Indexed for MEDLINE]

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