Project description:KaiC is the central cog of the circadian clock in Cyanobacteria. Close homologs of this protein are widespread among bacteria not known to have a circadian physiology. The function, interaction network, and mechanism of action of these KaiC homologs are still largely unknown. Here, we focus on KaiC homologs found in environmental Pseudomonas species. We characterize experimentally the only KaiC homolog present in Pseudomonas putida KT2440 and Pseudomonas protegens CHA0. Through phenotypic assays and transcriptomics, we show that KaiC is involved in osmotic and oxidative stress resistance in P. putida and in biofilm production in both P. putida and P. protegens.
Project description:The entire set of flagellar structural components and flagellar-specific transcriptional regulators, as well as much of the core chemotaxis machinery, is encoded into a >70 kbp cluster in Pseudomonas putida KT2440 genome. We have performed RNA-seq of the wild-type strain in order to identify operon boundaries and promoters location in this cluster.
Project description:The metabolically versatile Pseudomonas putida strain KT2440 is the first Gram-negative soil bacterium certified as a biosafety strain and is being used for applications in agriculture, biotechnology and bioremediation. P. putida has to cope in its niche with numerous abiotic stresses. The stress response to 4°C, pH 4.5, 0.8 M urea or 45 mM sodium benzoate, respectively, was analyzed by the global mRNA expression profile and screening for stress-intolerant Tn5 transposon mutants. In total we identified 49 gene regions to be differentially expressed and 32 genes in 22 operons to be indispensable for growth during exposure to one or the other abiotic stresses. We propose that stress is sensed by the outer membrane proteins OmlA and FepA and the inner membrane constituents PtsP, PhoPQ and CbrAB. The metabolic response is regulated by the cyo operon, the RelA/SpoT modulon, PcnB and VacB that control mRNA stability and BipA that exerts transcript-specific translational control. The adaptation of the membrane barrier, the uptake of phosphate, the maintenance of intracellular pH and redox status and the translational control of metabolism are the indispensable key mechanisms of the P. putida stress response. Keywords: functional genomics
Project description:The sigma factor FliA (σ28) has been described to activate the expression of several chemoreceptor-encoding genes and the late flagellar genes in Pseudomonas putida, enabling synthesis of the filament, an stator complex and completion of the flagella-associated chemotaxis machinery. The activity of FliA is repressed in the cytoplasm by the anti-sigma factor FlgM upon completion of the flagellar hook. In this study we aim to identify genome-wide targets of regulation by FliA in P. putida KT2442 (a spontaneous rifampicin-resistant mutant of the reference strain KT2440) by performing RNA-seq experiments using a fliA deletion mutant and a constitutively active strain that combines the deletion of flgM with ectopic production of FliA.
Project description:The bacterium Pseudomonas putida KT2440 has the ability to reduce selenite forming nanoparticles of elemental selenium. This is the transcriptome of the organism when cultured in the presence of selenite.
