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:Fluoride is the anionic form of fluorine, the 13th most abundant element in Earth's crust, and it is toxic to many organisms above a threshold concentration. Environmental bacteria can withstand relatively high fluoride concentrations, but the only mechanism described so far is the CrcB-dependent efflux. CrcB-mediated export is the primary mechanism of F-tolerance in the model environmental bacterium Pseudomonas putida, yet spontaneous NaF-tolerant mutants arise in the absence of the CrcB transporter, showing that this is not the sole pathway of tolerance. We used whole-genome sequencing, proteomic, and transcriptomic analyses to identify mechanisms that affect fluoride tolerance in Pseudomonas putida.
Project description:Pseudomonas putida KT2440 is a metabolically versatile soil bacterium useful both as a model biodegradative organism and as a host of catalytic activities of biotechnological interest. In this report, we present the high-resolution transcriptome of P. putida grown in different carbon sources as revealed by deep sequencing of the corresponding RNA pools. Examination of the data from growth on glycolytic (glucose, fructose) and gluconeogenic (succinate or glycerol) substrates revealed that > 20% of the P. putida genome is differentially expressed depending on the ensuing metabolic regime. Changes affected not only metabolic genes but also a suite of global regulators, e.g. the rpoS sigma subunit of RNAP, various cold-shock proteins and the three HU histone-like proteins. Specifically, the genes encoding HU subunit variants hupA, hupB and hupN drastically altered their expression levels (and thus their ability to form heterodimeric combinations) under the different growth conditions. Furthermore, we found that the two small RNAs crcZ and crcY, known to inhibit the Crc protein that mediates catabolite repression in P. putida, were both down-regulated by glucose.
Project description:Pseudomonas putida KT2440 is a metabolically versatile soil bacterium useful both as a model biodegradative organism and as a host of catalytic activities of biotechnological interest. In this report, we present the high-resolution transcriptome of P. putida grown in different carbon sources as revealed by deep sequencing of the corresponding RNA pools. Examination of the data from growth on glycolytic (glucose, fructose) and gluconeogenic (succinate or glycerol) substrates revealed that > 20% of the P. putida genome is differentially expressed depending on the ensuing metabolic regime. Changes affected not only metabolic genes but also a suite of global regulators, e.g. the rpoS sigma subunit of RNAP, various cold-shock proteins and the three HU histone-like proteins. Specifically, the genes encoding HU subunit variants hupA, hupB and hupN drastically altered their expression levels (and thus their ability to form heterodimeric combinations) under the different growth conditions. Furthermore, we found that the two small RNAs crcZ and crcY, known to inhibit the Crc protein that mediates catabolite repression in P. putida, were both down-regulated by glucose. cDNA libraries from Pseudomonas supplemented with different carbon sources (glucose, glycerol, fructose, succinate) were sequenced using HiSeq 2000 to yield 91 paired-end reads. Gene expression values were compared.