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Pseudomonas putida

About: Pseudomonas putida is a research topic. Over the lifetime, 6854 publications have been published within this topic receiving 230572 citations.


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Journal ArticleDOI
TL;DR: The repertoire of sigma factors in P. putida KT2440 was analysed and 19 of which corresponded to the subfamily of extracytoplasmic function (ECF) sigma Factors, which showed similarity to the Escherichia coli FecI sigma factor, which is involved in iron acquisition.
Abstract: Pseudomonas putida KT2440 is highly successful in colonizing a variety habitats, including aquatic and edaphic niches. In accordance with this ability and with the need to adapt to changing environmental conditions, P. putida has developed sophisticated mechanisms of transcriptional regulation. We analysed, at the genome level, the repertoire of sigma factors in P. putida KT2440 and identified 24 sigma factors, 19 of which corresponded to the subfamily of extracytoplasmic function (ECF) sigma factors. We detected 13 ECF sigma factors that showed similarity to the Escherichia coli FecI sigma factor, which is involved in iron acquisition. In 11 cases, a fecR-like gene was found adjacent to the fecI-like gene and, in 10 cases, a gene encoding an iron receptor lies in the vicinity of the fecI/fecR cluster. This may explain the ability of P. putida KT2440 to grow under low iron availability conditions. Five fecI/fecR/iron receptor gene clusters from P. putida were also identified in the human pathogen Pseudomonas aeruginosa.

104 citations

Journal ArticleDOI
TL;DR: Preliminary evidence suggests that the monooxygenase activity encoded by this DNA fragment is feedback-inhibited by phenols.
Abstract: Plasmid pJP4 enables Alcaligenes eutrophus JMP134 to degrade 3-chlorobenzoate and 2,4-dichlorophenoxyacetic acid (TFD). Plasmid pRO101 is a derivative of pJP4 obtained by insertion of Tn1721 into a nonessential region of pJP4. Plasmid pRO101 was transferred by conjugation to several Pseudomonas strains and to A. eutrophus AEO106, a cured isolate of JMP134. AEO106(pRO101) and some Pseudomonas transconjugants grew on TFD. Transconjugants with a chromosomally encoded phenol hydroxylase also degraded phenoxyacetic acid (PAA) in the presence of an inducer of the TFD pathway, namely, TFD or 3-chlorobenzoate. A mutant of one such phenol-degrading strain, Pseudomonas putida PPO300(pRO101), grew on PAA as the sole carbon source in the absence of inducer. This isolate carried a mutant plasmid, designated pRO103, derived from pRO101 through the deletion of a 3.9-kilobase DNA fragment. Plasmid pRO103 constitutively expressed the TFD pathway, and this allowed the metabolism of PAA in the absence of the inducer, TFD. Complementation of pRO103 in trans by a DNA fragment corresponding to the fragment deleted in pRO101 indicates that a negative control-regulatory gene (tfdR) is located on the BamHI E fragment of pRO101. Other subcloning experiments resulted in the cloning of the tfdA monooxygenase gene on a 3.5-kilobase fragment derived from pRO101. This subclone, in the absence of other pRO101 DNA, constitutively expressed the tfdA gene and allowed PPO300 to grow on PAA. Preliminary evidence suggests that the monooxygenase activity encoded by this DNA fragment is feedback-inhibited by phenols.

104 citations

Journal ArticleDOI
TL;DR: In studies of Pseudomonas putida IH-2000, a toluene-tolerant microorganism, membrane vesicles (MVs) were found to be released from the outer membrane when toLUene was added to the culture.
Abstract: Organic solvents are very toxic to microorganisms. Studies have shown that toluene destroys the inner membrane of gram-negative bacteria (7, 16, 35). However, Inoue and Horikoshi discovered the toluene-tolerant strain Pseudomonas putida IH-2000 (11). It has been demonstrated that the degree of toxicity of an organic solvent corresponds to its log Pow value, which is the logarithm of the partition coefficient of the organic solvent between n-octanol and water (11). Organic solvents with a lower log Pow have higher toxicity to microorganisms (12). Many reports have described Pseudomonas strains that were toluene tolerant (6, 14, 27, 32). Organic solvent-tolerant microorganisms have attracted interest due to the possibility of applying them to persolvent fermentation of water-insoluble compounds (5). We have studied the mechanisms of toluene tolerance in P. putida IH-2000, and there have been various reports about such mechanisms in Pseudomonas species. The mechanisms of organic solvent tolerance have been shown to involve active efflux pumps (13, 20, 26, 30); low cell hydrophobicity, which serves to keep solvent molecules away from the cell surface (2, 21); and low fluidity of the bacterial membrane, to protect the cell from the solvent (8, 10, 17). In these studies, many mutants either tolerant or sensitive to organic solvents have been isolated from Pseudomonas or Escherichia coli (4, 15, 29). These mutants showed phenotypic changes not only in solvent tolerance levels but also in antibiotic resistance levels (4, 15). We have reported the isolation of a toluene-sensitive mutant, strain 32, which showed unchanged antibiotic resistance levels, obtained through transposon mutagenesis using Tn5. The gene disrupted by insertion of Tn5 was identified as cyoC, which is one of the subunits of cytochrome o (21). The outer membrane protein profile and lipid composition of lipopolysaccharides (LPS) of strain 32 were found to differ from those of IH-2000. Furthermore, the cell surface hydrophobicity of strain 32 was greater than that of IH-2000 (21). Even if the cell surface shows very low hydrophobicity, organic solvent molecules intercalate into and accumulate in the cell membrane and finally disrupt its structural integrity (34). The toluene molecules adhering to the cell membrane must be eliminated. Active efflux pump systems have been reported elsewhere to serve as one of the mechanisms of toluene elimination (13, 20, 26, 30). We report here a novel toluene tolerance system in P. putida IH-2000 which involves the elimination of toluene from the outer membrane through the release of membrane vesicles (MVs) composed of phospholipids and LPS. This defense system appears to represent a novel function of the outer membrane of gram-negative bacteria.

104 citations

Journal ArticleDOI
TL;DR: The responses of Pseudomonas putida KT2442 to various forms of nutrient starvation and stress conditions were examined by two-dimensional polyacrylamide electrophoresis and a new class of transiently expressed proteins, referred to as maturation proteins, took place.
Abstract: The responses of Pseudomonas putida KT2442 to various forms of nutrient starvation and stress conditions were examined by two-dimensional polyacrylamide electrophoresis. Carbon deprivation resulted in a temporal expression of two classes of starvation-induced proteins: one class was transiently expressed during the initial phase of starvation, and the second class was expressed throughout the entire starvation period. Proteins of the second class could be further subdivided into proteins induced specifically under conditions of carbon starvation, proteins also induced by conditions of stress created by elevated temperature and osmolarity, and finally proteins that were also induced by conditions of nitrogen as well as phosphate starvation. Addition of glucose to a carbon-starved culture led to initiation of a recovery phase. During this phase, repression of starvation-induced proteins as well as induction of a new class of transiently expressed proteins, referred to as maturation proteins, took place.

104 citations

Journal ArticleDOI
TL;DR: The Crc protein is a translational repressor that recognizes a specific target at some mRNAs, controlling catabolite repression and co‐ordinating carbon metabolism in pseudomonads, and it is proposed that CrcZ and CrcY act in concert, sequestering and modulating the levels of free Crc according to metabolic conditions.
Abstract: The Crc protein is a translational repressor that recognizes a specific target at some mRNAs, controlling catabolite repression and co-ordinating carbon metabolism in pseudomonads. In Pseudomonas aeruginosa, the levels of free Crc protein are controlled by CrcZ, a sRNA that sequesters Crc, acting as an antagonist. We show that, in Pseudomonas putida, the levels of free Crc are controlled by CrcZ and by a novel 368 nt sRNA named CrcY. CrcZ and CrcY, which contain six potential targets for Crc, were able to bind Crc specifically in vitro. The levels of CrcZ and CrcY were low under conditions generating a strong catabolite repression, and increased strongly when catabolite repression was absent. Deletion of either crcZ or crcY had no effect on catabolite repression, but the simultaneous absence of both sRNAs led to constitutive catabolite repression that compromised growth on some carbon sources. Overproduction of CrcZ or CrcY significantly reduced repression. We propose that CrcZ and CrcY act in concert, sequestering and modulating the levels of free Crc according to metabolic conditions. The CbrA/CbrB two-component system activated crcZ transcription, but had little effect on crcY. CrcY was detected in P. putida, Pseudomonas fluorescens and Pseudomonas syringae, but not in P. aeruginosa.

104 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023184
2022345
2021182
2020246
2019226
2018206