The effect of iron limitation on the transcriptome and proteome of Pseudomonas fluorescens Pf-5.
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.
Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, Australia.
Chee Kent
CK
Lim
Karl A
KA
Hassan
Sasha G
SG
Tetu
Joyce E
JE
Loper
Ian T
IT
Paulsen
D001426:Bacterial Proteins / Q000378:metabolism; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D016000:Cluster Analysis; D004579:Electron Transport / Q000235:genetics; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D055442:Metabolome / Q000235:genetics; D009154:Mutation; D018384:Oxidative Stress; D020543:Proteome; D011551:Pseudomonas fluorescens / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000235:genetics; D017262:Siderophores / Q000378:metabolism; D012808:Sigma Factor / Q000378:metabolism; D059467:Transcriptome
D001426:Bacterial Proteins; D008565:Membrane Proteins; D020543:Proteome; D012269:Ribosomal Proteins; D017262:Siderophores; D012808:Sigma Factor; C057616:tonB protein, Bacteria; D007501:Iron