Submitted to: Pseudomonas
Publication Type: Abstract Only
Publication Acceptance Date: 8/29/2011
Publication Date: 9/4/2011
Citation: Lim, C., Hassan, K., Penesyan, A., Loper, J.E., Paulsen, I. 2011. The effect of zinc limitation on the transcriptome of Pseudomonas fluorescens Pf-5. Pseudomonas. 2011. 13th International Conference abstract book. Pg. 37. Interpretive Summary:
Technical Abstract: Pseudomonas fluorescens Pf-5 is a soil bacterium that can protect several plant species from diseases caused by fungal and bacterial pathogens. Zinc is a vital micronutrient for bacteria but is deficient in some soil environments and toxic in large quantities. Hence, bacteria have evolved elaborate zinc homeostasis mechanisms to regulate the delicate balancing of intracellular zinc concentrations. To investigate the effect of zinc limitation on Pf-5, we performed a transcriptomic profiling experiment using a genomic microarray to compare cells grown under zinc-replete and zinc-limited conditions. The transcription of 73 genes was upregulated by at least 2-fold by zinc limitation, whereas 28 genes were transcriptionally downregulated. One of the most prominent effects of zinc starvation was the overexpression of the putative zinc uptake regulator (ZUR). Using a bioinformatics approach, the putative binding sites for this regulator were identified in the Pf-5 genome and were correlated with expression data. Additionally, the genes encoding a number of transporter systems probably involved in zinc transport, including TonB-dependent receptors, ABC transporters, outer membrane porins and an RND efflux system, were also transcriptionally regulated by zinc limitation. Interestingly, zinc limitation also had a profound influence on the expression of genes encoding for ribosomal proteins (L31 and L36) as well as basic metabolic functions. Several of these changes appear to reflect a shift in the physiology of Pf-5 that reduces its reliance on zinc. Important to the biocontrol phenotypes of Pf-5, we observed the decreased transcription of genes involved in the biosynthesis of the 2,4-diacetylphloroglucinol antibiotic. Together these results demonstrate a broad transcriptomic influence of zinc and highlight the importance of this micronutrient in dictating the molecular physiology of Pf-5.