Zinc‐dependent Transcriptional Regulation in Paracoccus denitrificans

Abstract

Zinc is an essential trace element required for every organism but it is toxic when present in high concentrations. Therefore, maintaining zinc homeostasis within a narrow range is a critical process for the growth and survival of bacteria that is also essential for bacterial virulence. Zinc homeostasis in bacteria is maintained in response to diverse environmental Zn concentration by a set of different importers and exporters. Importers include high‐affinity Zn binding ABC transporters of cluster A‐I family, which are under the control of the zinc uptake regulator (Zur). Zur is a transcription factor that binds promoter elements upstream of these genes only in the zinc‐bound form, thereby mediating zinc‐dependent repression. Here we have employed RNA‐Seq to identify genes differentially expressed under conditions of zinc limitation and study if these genes are regulated by Zur in Paracoccus denitrificans. The results showed the differential expression of 147 genes, of which 133 genes were up‐regulated under conditions of zinc limitation while only 14 were significantly down‐regulated. Up‐regulated genes included several transcription factors including zur, transition metal importers including Zn importers, metabolic genes and other hypothetical proteins. Intriguingly, we have also observed very high expression of components of denitrification such as nitric oxide reductase (norCB) and nitrite reductase (nirS). These were found to be directly regulated by Zur thereby showing the link between denitrification and zinc homeostasis in P. denitrificans.Support or Funding InformationNCGR and INBRE Funding ‐ 8P20GM103451‐12NIH SC2 GM111170‐01