The effect of iron limitation on the transcriptome and proteome of Pseudomonas fluorescens Pf-5

PLoS One. 2012;7(6):e39139. doi: 10.1371/journal.pone.0039139. Epub 2012 Jun 18.

Abstract

One of the most important micronutrients for bacterial growth is iron, whose bioavailability in soil is limited. Consequently, rhizospheric bacteria such as Pseudomonas fluorescens employ a range of mechanisms to acquire or compete for iron. We investigated the transcriptomic and proteomic effects of iron limitation on P. fluorescens Pf-5 by employing microarray and iTRAQ techniques, respectively. Analysis of this data revealed that genes encoding functions related to iron homeostasis, including pyoverdine and enantio-pyochelin biosynthesis, a number of TonB-dependent receptor systems, as well as some inner-membrane transporters, were significantly up-regulated in response to iron limitation. Transcription of a ribosomal protein L36-encoding gene was also highly up-regulated during iron limitation. Certain genes or proteins involved in biosynthesis of secondary metabolites such as 2,4-diacetylphloroglucinol (DAPG), orfamide A and pyrrolnitrin, as well as a chitinase, were over-expressed under iron-limited conditions. In contrast, we observed that expression of genes involved in hydrogen cyanide production and flagellar biosynthesis were down-regulated in an iron-depleted culture medium. Phenotypic tests revealed that Pf-5 had reduced swarming motility on semi-solid agar in response to iron limitation. Comparison of the transcriptomic data with the proteomic data suggested that iron acquisition is regulated at both the transcriptional and post-transcriptional levels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / metabolism
  • Biological Transport
  • Cell Membrane / metabolism
  • Cluster Analysis
  • Electron Transport / genetics
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial
  • Iron / metabolism*
  • Membrane Proteins / metabolism
  • Metabolome / genetics
  • Mutation
  • Oxidative Stress
  • Proteome*
  • Pseudomonas fluorescens / genetics*
  • Pseudomonas fluorescens / growth & development
  • Pseudomonas fluorescens / metabolism*
  • Ribosomal Proteins / genetics
  • Siderophores / metabolism
  • Sigma Factor / metabolism
  • Transcriptome*

Substances

  • Bacterial Proteins
  • Membrane Proteins
  • Proteome
  • Ribosomal Proteins
  • Siderophores
  • Sigma Factor
  • tonB protein, Bacteria
  • Iron